Surgery Shows Survival Benefit in Early Prostate Cancer
- pdf original study attached
Download the PDF|
"As of the current follow-up analysis, there continues to be a significant reduction in the rate of death from any cause, the rate of death from prostate cancer, and the risk of metastases in the radical-prostatectomy group as compared with the watchful-waiting group. The benefit is obvious among men younger than 65 years of age, but it is still unclear whether the benefit extends to older men. The risk of death from prostate cancer after radical prostatectomy among men who had tumors with extracapsular growth, as compared with men who had tumors without extracapsular growth, was increased by a factor of 7. We also observed a benefit of radical prostatectomy among men with low-risk tumors."
Published: May 04, 2011
Younger men with early-stage prostate cancer had a significantly lower mortality risk with radical prostatectomy compared with watchful waiting, long-term follow-up from a Scandinavian study showed.
Surgery was associated with almost a 50% reduction in the relative risk of prostate cancer death at 15 years among men younger than 65 with low-risk disease, as reported in the May 5 issue of the New England Journal of Medicine. All-cause mortality was about 40% lower.
The results in younger men with low-risk prostate cancer drove the overall outcome, which showed a 38% reduction in prostate cancer mortality with radical prostatectomy, Anna Bill-Axelson, MD, PhD, of University Hospital in Uppsala, Sweden, and co-authors wrote.
* Explain that further follow-up of a Scandinavian study showed that patients undergoing radical prostatectomy had a survival advantage over those treated with watchful waiting.
* Note that the advantage was seen only in patients under the age of 65, but that subgroup analyses were hampered by lack of power.
Men ages 65 and older did not benefit significantly from radical prostatectomy versus watchful waiting, regardless of disease characteristics.
"The benefit is obvious among men younger than 65 years of age, but it is still unclear whether the benefit extends to older men," the investigators wrote.
The number needed to treat (NNT) declined from 19 in an earlier analysis to 15 after a median follow-up of 12.8 years. Among men younger than 65, the NNT was seven.
The findings came from the latest analysis of the Scandinavian Prostate Cancer Group Study Number 4. Earlier analyses showed a significant reduction in prostate cancer mortality and death from any cause in men randomized to radical prostatectomy versus watchful waiting. However, the benefit was limited to men younger than 65.
In the earlier analyses, too few prostate cancer deaths had occurred among men with low-risk disease to determine whether that subgroup also benefited from surgery, the authors noted. Longer follow-up offered the potential to make that determination.
The trial involved 695 men with early-stage prostate cancer, randomized from October 1989 to February 1999 to surgery or watchful waiting. The study population had a mean age of 65 and a baseline PSA level that averaged 13 ng/mL.
By the end of 2009, 166 men in the surgery group and 201 in the watchful-waiting arm had died. The estimated 15-year mortality was 46% with surgery and 52.7% with watchful waiting, which translated into a 25% reduction in the relative risk of death in favor of prostatectomy (P=0.007).
The authors found that 55 men in the radical-prostatectomy arm and 81 in the watchful-waiting group had died of prostate cancer, a 38% reduction in the relative risk (P=0.01). The incidence of distant metastasis was 4.8% in the prostatectomy arm and 18.6% with watchful waiting, a 41% reduction in relative risk (P<0.001).
Subgroup analysis showed that surgically treated men younger than 65 had significant reductions in relative risk for overall mortality, prostate cancer mortality, and distant metastases, averaging about 50%. In contrast, surgery did not significantly reduce the risk of any of the three endpoints in older men.
The study population included 263 men with low-risk prostate cancer, defined as a PSA level <10 ng/mL and either a Gleason score <7 or WHO grade 1. In that subgroup, surgery was associated with significant reduction in all-cause mortality (31.4% versus 44.6%, P=0.02) and the risk of distant metastases (9.9% versus 21.4%, P=0.008) but not prostate cancer mortality (6.8% versus 11.0%, P=0.14).
Further stratified by age, the data showed that men younger than 65 with low-risk prostate cancer also derived significant benefits from surgery with respect to all-cause mortality and distant metastases, but surgery did not improve mortality or the risk of distant metastases in older men.
"The accruing numbers of events for the older age group indicate that in our study, a reduction in disease-specific mortality is unlikely ever to become apparent in this age group, owing to competing causes of death," the authors wrote in conclusion.
Limitations of the study included lack of power in the subgroup analyses, differences in screening and biopsy protocols for low-risk patients treated with active surveillance now versus at the time of enrollment in the study, and reliance on medical record review versus patient report for symptom severity.
The authors had no relevant disclosures.
Primary source: New England Journal of Medicine
Bill-Axelson A, et al "Radical prostatectomy versus watchful waiting in early prostate cancer" N Engl J Med 2011; 364: 1708-1717.
Effective Treatment for Early-Stage Prostate Cancer - Possible, Necessary, or Both?
Matthew R. Smith, M.D., Ph.D.
From the Genitourinary Malignancies Program, Massachusetts General Hospital Cancer Center, Boston.
N Engl J Med 2011; 364:1770-1772 May 5, 2011
In 2010, prostate cancer was diagnosed in approximately 217,000 men in the United States. More than 90% of patients with newly diagnosed prostate cancer have localized (clinical stage T1 or T2) disease.1 Men with early-stage prostate cancer face the treatment dilemma posed by the urologist Dr. Willet Whitmore: ŇIf treatment for cure is necessary, is it possible? If possible, is it necessary?Ó
The Scandinavian Prostate Cancer Group Study 4 (SPCG-4) has provided important evidence that effective treatment is both necessary and possible for many men with early-stage prostate cancer. In a 2008 report of SPCG-4, radical prostatectomy, as compared with watchful waiting, was associated with improved prostate-cancerĐspecific and overall survival in men with early-stage prostate cancer (clinical stage T1 or T2, well-differentiated or moderately well-differentiated histologic findings, and a prostate-specific antigen [PSA] level of <50 ng per milliliter).2 In this issue of the Journal, Bill-Axelson et al. update the results of the SPCG-4 study.3 After a median follow-up of 12.8 years, prostatectomy remained associated with greater prostate-cancerĐspecific and overall survival. Almost two thirds of the deaths were unrelated to prostate cancer. The survival benefit with prostatectomy was restricted to men younger than 65 years of age and was also evident in a subgroup of men who were categorized as having low-risk disease (Gleason score [the sum of the two most common histologic patterns or grades in a prostate tumor, each of which is graded on a scale of 1 to 5, with 5 indicating the most cytologically aggressive pattern] of <7 and PSA level of <10 ng per milliliter).
The survival benefit with prostatectomy in men with low-risk disease is the most important new finding of SPCG-4 but may not be relevant for men with low-risk early-stage prostate cancers identified by PSA screening. In SPCG-4, the mean age of the patients was 65 years, 88% had palpable tumors, and the cancers were diagnosed by means of screening tests in only 5.2% of the patients. Among men with newly diagnosed prostate cancer in the United States, the median age is 67 years, fewer than 50% have palpable tumors, and most cancers are identified through screening tests.1 The lead-time bias associated with PSA screening has been estimated to be as long as 10 years.4 In SPCG-4, the number of men needed to treat with prostatectomy to prevent one death at 15 years was 15. The predicted number needed to treat is substantially greater for contemporary men with low-risk prostate cancers detected by PSA screening because the rates of death from prostate cancer are lower in this group.
Recent studies of radiation therapy provide additional evidence of the importance of local and regional control of the disease in men with prostate cancer. In the Scandinavian Prostate Cancer Group Study 7 (SPCG-7) involving men with high-risk prostate cancer, the addition of radiation therapy to androgen-deprivation therapy, as compared with androgen-deprivation therapy alone, was associated with greater disease-specific and overall survival.5 Three randomized trials have shown that the clinical outcomes are improved when adjuvant radiation therapy is given after prostatectomy in men with pathological stage T3 disease, positive surgical margins, or both. In a Southwest Oncology Group study involving men with pT3N0 prostate cancer, adjuvant radiation therapy was associated with improved metastasis-free and overall survival.6 The number of men with pT3 disease needed to treat with adjuvant radiation therapy to avert one death at 12.6 years was 9.1, a figure similar to the number needed to treat in SPCG-4.
There are no data from large, randomized, controlled trials regarding the comparative effectiveness of prostatectomy and radiation therapy in patients with early-stage prostate cancer. Although large observational studies are limited by selection bias and other potential confounding factors, they have shown similar long-term rates of disease control with prostatectomy and radiation therapy.7 The rapid evolution of surgical and radiation-therapy techniques further complicates the comparison of surgery with radiation therapy. Advancements in the accurate delivery of radiation therapy, including conformal and image-guided therapy, have allowed for an escalation in the dose of radiation, with associated improvements in the rates of disease control.
All forms of treatment for prostate cancer have potential adverse effects. Prostatectomy is associated with erectile dysfunction and urinary incontinence. External-beam radiation therapy is associated with erectile dysfunction and bowel symptoms. Watchful waiting also has potential consequences with respect to quality of life. In SPCG-4, 40% of the men assigned to prostatectomy and 63% of men assigned to watchful waiting subsequently received androgen-deprivation therapy. Androgen-deprivation therapy is associated with sexual dysfunction, vasomotor flushing, and fatigue. Androgen-deprivation therapy also increases fat mass, decreases muscle mass, decreases insulin sensitivity, and alters serum lipid profiles.8 Consistent with these adverse metabolic effects, androgen deprivation has been linked to greater risks for diabetes and coronary heart disease.9
Two large, randomized, controlled trials are under way to determine whether treatment will reduce mortality in men with prostate cancers identified through PSA screening. The Prostate Cancer Intervention versus Observation Trial (PIVOT; ClinicalTrials.gov number, NCT00007644) is a randomized trial of prostatectomy versus observation in men with early-stage prostate cancer. PIVOT completed enrollment of 731 men in 2002; the planned follow-up period is 15 years.10,11 In contrast to the watchful-waiting group in SPCG-4, patients in the observation group of PIVOT are monitored closely and offered surgery, radiation therapy, or androgen-deprivation therapy at the time of disease progression. The Prostate Testing for Cancer and Treatment trial (ProtecT, NCT00632983) in the United Kingdom is a randomized treatment trial nested within a prostate-cancer screening study.11 In the ProtecT study, more than 2500 men with early-stage prostate cancer have been randomly assigned to prostatectomy, radiation therapy, or observation. The results of the PIVOT and ProtecT trials will help inform future decisions about the treatment of low-risk prostate cancer, but many challenges will remain. Management of early-stage prostate cancer will continue to require careful consideration of the severity of the disease, the potential benefits and harms of intervention, and the patient's age, health status, and individual preferences.
Radical Prostatectomy versus Watchful Waiting in Early Prostate Cancer
N Engl J Med 2011 May 5, 2011
*The Scandinavian Prostate Cancer Group
Anna Bill-Axelson, M.D., Ph.D., Lars Holmberg, M.D., Ph.D., Mirja Ruutu, M.D., Ph.D., Hans Garmo, Ph.D., Jennifer R. Stark, Sc.D., Christer Busch, M.D., Ph.D., Stig Nordling, M.D., Ph.D., Michael Hggman, M.D., Ph.D., Swen-Olof Andersson, M.D., Ph.D., Stefan Bratell, M.D., Ph.D., Anders Spngberg, M.D., Ph.D., Juni Palmgren, Ph.D., Gunnar Steineck, M.D., Ph.D., Hans-Olov Adami, M.D., Ph.D., and Jan-Erik Johansson, M.D., Ph.D., for the SPCG-4 Investigators*
From the Department of Urology (A.B.-A., M.H.), Regional Oncologic Center (L.H., H.G.), and Department of Pathology (C.B.), University Hospital, Uppsala; the Division of Clinical Cancer Epidemiology, Department of Oncology and Pathology (A.B.-A., G.S.), and the Department of Medical Epidemiology and Biostatistics (J.P., H.-O.A.), Karolinska Institute, Stock- holm; the Department of Urology (J.R.S., S.O.-A., J.-E.J.), Center for Assessment of Medical Technology (J.-E.J.),
rebro; the Department of Urology, Bors Hospital, Bors (S.B.); the Department of Urology, Linkping University Hospital, Linkping (A.S.); and the Division of Clinical Cancer Epidemiology, Sahlgrenska Academy, Go- thenburg (G.S.) - all in Sweden; KingŐs College London School of Medicine, Di- vision of Cancer Studies, London (L.H., H.G.); the Departments of Urology (M.R.) and Pathology (S.N.), Helsinki University Central Hospital, Helsinki; and Channing Laboratory, Department of Medicine, Brigham and WomenŐs Hospital and Harvard Medical School (J.R.S.), and the Department of Epidemiology, Harvard School of Public Health (H.-O.A.) - both in Boston. Address reprint requests to Dr. Bill-Axelson at the Department of Urology, Uppsala University Hospital, 75185 Uppsala, Sweden, or at anna.bill .email@example.com.
Background: In 2008, we reported that radical prostatectomy, as compared with watchful waiting, reduces the rate of death from prostate cancer. After an additional 3 years of follow-up, we now report estimated 15-year results.
Methods: From October 1989 through February 1999, we randomly assigned 695 men with early prostate cancer to watchful waiting or radical prostatectomy. Follow-up was complete through December 2009, with histopathological review of biopsy and radical-prostatectomy specimens and blinded evaluation of causes of death. Relative risks, with 95% confidence intervals, were estimated with the use of a Cox proportional-hazards model.
Results: During a median of 12.8 years, 166 of the 347 men in the radical-prostatectomy group and 201 of the 348 in the watchful-waiting group died (P=0.007). In the case of 55 men assigned to surgery and 81 men assigned to watchful waiting, death was due to prostate cancer. This yielded a cumulative incidence of death from prostate cancer at 15 years of 14.6% and 20.7%, respectively (a difference of 6.1 percentage points; 95% confidence interval [CI], 0.2 to 12.0), and a relative risk with surgery of 0.62 (95% CI, 0.44 to 0.87; P=0.01). The survival benefit was similar before and after 9 years of follow-up, was observed also among men with low-risk prostate cancer, and was confined to men younger than 65 years of age. The number needed to treat to avert one death was 15 overall and 7 for men younger than 65 years of age. Among men who underwent radical prostatectomy, those with extracapsular tumor growth had a risk of death from prostate cancer that was 7 times that of men without extracapsular tumor growth (relative risk, 6.9; 95% CI, 2.6 to 18.4).
Conclusions: Radical prostatectomy was associated with a reduction in the rate of death from prostate cancer. Men with extracapsular tumor growth may benefit from adjuvant local or systemic treatment. (Funded by the Swedish Cancer Society and the National Institutes of Health.)
The randomized Scandinavian Prostate Cancer Group Study Number 4 (SPCG-4) showed that radical prostatectomy decreased the risk of metastases, the rate of death from prostate cancer, and the rate of death from any cause.1-3 Although the participants in SPCG-4 were predominantly men whose cancers were detected on the basis of symptoms, rather than by elevated prostate-specific antigen (PSA) levels, prostate-cancer events have also accumulated during an extended follow-up period in a subgroup of men with low-risk disease. Determining whether there is a survival benefit for men with low-risk disease is relevant in light of the risk of overdiagnosis resulting from PSA testing and the adverse events associated with therapy.4 Whether the previously observed lack of benefit in men older than 65 years of age and the absence of increased benefit after 9 years of follow-up persist is also of interest. We now present estimates of 15-year results, with a median follow-up period of 12.8 years.
Between October 1989 and December 1999, at 14 centers in Sweden, Finland, and Iceland, we randomly assigned 695 men with newly diagnosed, localized prostate cancer to radical prostatectomy or watchful waiting, as described in detail in a previous report1 and in the study protocol (available with the full text of this article at NEJM.org). The study was approved by the regional ethics committee for each participating center. Oral informed consent was obtained from all eligible patients.
Men were eligible for inclusion in the study if they were younger than 75 years of age and had a life expectancy of more than 10 years, had no other known cancers, and had a localized tumor of stage T0d (later named T1b), T1, or T2, as assessed according to the 1978 criteria of the International Union against Cancer. After revision of the staging criteria in 1987, T1c tumors were also included starting in 1994.5 On the basis of the results of a core biopsy or fine-needle aspiration, the tumor had to be well differentiated to moderately well differentiated according to the World Health Organization (WHO) classification. All patients included in the study were required to have a serum PSA level of less than 50 ng per milliliter and a negative bone scan.
For men assigned to the radical-prostatectomy group, the surgical procedure started with a lymphadenectomy of the obturator fossa6; if no nodal metastases were found in frozen sections, the radical prostatectomy was performed.7 Radical excision of the tumor was given priority over nerve-sparing surgery. Men who were assigned to the watchful-waiting group did not receive any immediate treatment.
If signs of local recurrence (a palpable nodule or histologically confirmed recurrence) developed in a patient in the radical-prostatectomy group, hormonal therapy was initiated. Men in the watchful-waiting group who had signs of obstructive voiding disorders were treated with transurethral resection. Metastases detected by bone scan were managed with hormonal therapy. In 2003, after the introduction of antiandrogens, clinicians were allowed to initiate hormonal treatment if there were signs of tumor progression, including elevations in PSA level, and if they believed that hormonal treatment would be beneficial to the patient.
In 1999, all core biopsy specimens were reviewed by four uropathologists and graded with the use of Gleason scores.8 (The Gleason score is the sum of the two most common histologic patterns or grades in a prostate tumor, each of which is graded on a scale of 1 to 5, with 5 indicating the most aggressive pattern.) The pathologists were unaware of the patient's study assignment and of the outcome of the cancer. In 2006, the same four pathologists and one additional pathologist reviewed all radical-prostatectomy specimens, graded them with the use of Gleason scores, evaluated extracapsular tumor growth, and examined the surgical margins. Seminal vesicle involvement was assessed as extracapsular tumor growth. For 256 of the specimens, concordance between the preoperative and the postoperative Gleason scores could be evaluated. Full concordance was noted in the scores for 32% of the specimens, and postoperative Gleason scores were lower in 10%, one step higher in 30%, and two or more steps higher in 28%.
Patients were followed every 6 months for 2 years and annually thereafter. Initially, bone scans were obtained annually; after 2003, they were obtained every second year. Metastases were defined as metastatic lesions that were visible on a bone scan or histologically confirmed soft-tissue metastases outside the pelvic area. In the radical-prostatectomy group, local recurrence was defined as the presence of a palpable mass on digital rectal examination or a histologically confirmed tumor on rectal biopsy. In the watchful-waiting group, tumor progression was defined as palpable extracapsular extension or symptoms of obstructive voiding necessitating intervention. All medical records were reviewed for information on events related to prostate cancer as well as on side effects of surgery reported by the attending urologist.
In the case of patients who died, an end-point committee, whose members were unaware of the treatment assignments, determined the cause of death on the basis of information extracted from the patient's medical records, using a protocol that defined disease progression according to increased elevations in PSA levels, development of metastases, and the need for hormonal treatments and palliative treatments. All participants were followed through December 31, 2009, and no patient was lost to follow-up. The three members of the end-point committee (see the Supplementary Appendix, available at NEJM.org) determined the cause of death individually; for cases in which there was disagreement among the members regarding the cause of death, the group met to reach consensus.
Analyses have been performed every third year according to the protocol. We analyze three different end points: death from any cause, death from prostate cancer (with death from other causes treated as a competing risk), and the risk of metastases (with death from all causes treated as a competing risk). Relative risks and 95% confidence intervals, as well as differences in cumulative incidence (with 95% confidence intervals) are reported for each end point. Relative risks were estimated with the use of Cox proportional-hazards models. Proportionality was verified by means of visual inspection of the parallelisms of the logarithms of the estimated cumulative hazards and was further tested with an analysis conditioned on 9-year survival. Cumulative incidence was assessed to account for competing risks.9 We used Gray's test to assess differences in cumulative incidence.10 The effect of radical prostatectomy on nonfatal end points was estimated by calculating the difference between the study groups in the cumulative incidence of local progression and of the initiation of hormonal and other palliative treatments, including palliative radiation, cytotoxic drugs, and laminectomy.
To assess the possible modification of the treatment effect according to patient characteristics, analyses were performed in subgroups according to age (<65 vs. ≥65 years), PSA level at the time of diagnosis (<10 vs. ≥10 ng per milliliter), and Gleason score (<7 vs. ≥7). These three subgroup analyses were not included in the main protocol but were specified before any data were seen. Any modification of the effect of radical prostatectomy was tested in the Cox proportional-hazards model by including an interaction term between subgroup category and randomization group. We further explored the interaction by including the three possible effect modifiers (age, PSA level, and Gleason score) as continuous variables in the model. When there was evidence of effect modification, we further controlled for age, PSA level, tumor stage (T1b, T1c, or T2), Gleason score, and year of enrollment.
We similarly explored the effect of radical prostatectomy in a low-risk group, which was defined as men with a PSA level of less than 10 and a tumor with either a Gleason score less than 7 or a WHO grade of 1 (in the case of tumors that were diagnosed only by cytologic assessment). We also assessed the prognostic ability of three histopathological characteristics of the radical-prostatectomy specimens: margins (positive vs. negative), extracapsular tumor growth (not present vs. any extension), and Gleason score (2 to 6, 7, or 8 to 10). One model included the histopathological characteristic of interest with adjustment for age group. Another model included the histopathological characteristic of interest with adjustment for the two other histopathological characteristics and age group.
A total of 347 men were assigned to the radical-prostatectomy group, and 348 to the watchful-waiting group. The baseline characteristics of the two groups were similar; the mean age of the men in both groups was 65 years. Only 12% of the patients had nonpalpable T1c tumors at the time of enrollment in the study. The mean PSA level was approximately 13 ng per milliliter (Table 1 in the Supplementary Appendix). By December 31, 2009, a total of 294 men in the radical-prostatectomy group had undergone a radical prostatectomy, and 302 men in the watchful-waiting group had not undergone curative treatment (Fig. 1 in the Supplementary Appendix). The median follow-up time was 12.8 years (range, 3 weeks to 20.2 years).
A total of 367 of the 695 men enrolled in the study had died by the end of 2009 - 166 in the radical-prostatectomy group and 201 in the watchful-waiting group. The cumulative incidence of death at 15 years was 46.1% in the radical-prostatectomy group and 52.7% in the watchful-waiting group (a difference of 6.6 percentage points; 95% confidence interval [CI], -1.3 to 14.5), corresponding to a relative risk of death in the radical-prostatectomy group of 0.75 (95% CI, 0.61 to 0.92; P=0.007) (Figure 1AFigure 1Cumulative Incidence of Death from Any Cause, Death from Prostate Cancer, and Development of Metastases. and Table 1Table 1Cumulative Incidence, Absolute Risk Reduction, and Relative Risk for Death from Any Cause, Death from Prostate Cancer, and Development of Distant Metastases. and Table 2Table 2Cause of Death According to Treatment Group and Age at Diagnosis.) and a number needed to treat of 15. One man in the radical-prostatectomy group died postoperatively.
By the end of 2009, a total of 55 men in the radical-prostatectomy group and 81 men in the watchful-waiting group had died of prostate cancer. The cumulative incidence of death at 15 years was 14.6 in the radical-prostatectomy group and 20.7 in the watchful-waiting group (a difference of 6.1 percentage points; 95% CI, 0.2 to 12.0), corresponding to a relative risk of death in the radical-prostatectomy group of 0.62 (95% CI, 0.44 to 0.87; P=0.01) (Figure 1B and Table 1 and Table 2). The Cox proportional-hazards analysis conditioned on 9-year survival showed differences in survival patterns that were similar to those in the main analysis (data not shown).
Distant metastases were diagnosed in 81 men in the radical-prostatectomy group and 123 men in the watchful-waiting group by the end of 2009. The cumulative incidence of distant metastases at 15 years was 21.7% in the radical-prostatectomy group and 33.4% in the watchful-waiting group (a difference of 11.7 percentage points; 95% CI, 4.8 to 18.6), corresponding to a relative risk of distant metastases in the radical-prostatectomy group of 0.59 (95% CI, 0.45 to 0.79; P<0.001) (Figure 1C and Table 1 and Table 2).
Nonfatal End Points
Local progression occurred in 74 men in the radical-prostatectomy group and 169 men in the watchful-waiting group. The cumulative incidence of local progression at 15 years was 21.5% and 49.3%, respectively (a difference of 27.9 percentage points; 95% CI, 20.9 to 34.8), corresponding to a relative risk of local progression in the radical-prostatectomy group of 0.34 (95% CI, 0.26 to 0.45). A total of 139 men in the radical-prostatectomy group, as compared with 223 men in the watchful-waiting group, received hormonal therapy; the cumulative incidence was 39.6% and 63.4%, respectively (a difference of 23.8 percentage points; 95% CI, 16.4 to 31.2).
Table 3Table 3Nonfatal Surgical Complications within 1 Year after Surgery among Men in the Radical-Prostatectomy Group. shows the 1-year cumulative incidence of postoperative complications as noted in the medical records. The most common symptom reported was impotence (58% of patients), followed by urinary leakage (32%).
The PSA level at the time of diagnosis (<10 vs. ≥10 ng per milliliter) and the Gleason score (<7 vs. ≥7) did not alter the effect of radical prostatectomy (P=0.72 and P=0.36, respectively, for the interaction with respect to overall survival, and P=0.30 and P=0.52, respectively, for the interaction with respect to cause-specific survival). The interaction term between age at randomization (<65 years vs. ≥65 years) and treatment was significant with respect to overall mortality (P=0.003) and remained so when age was considered as a continuous variable (P=0.001). The P value for the interaction between age and treatment with respect to death from prostate cancer was 0.16. There was a significant reduction in all three investigated end points among men who were younger than 65 years of age. The relative risk reduction ranged from 48% to 53%, and the absolute risk reduction ranged from 9 percentage points to 18 percentage points at 15 years; the number needed to treat was seven (Figure 1G, 1H, and 1I and Table 1). Among men 65 years of age or older, there was no significant reduction in any of the three investigated end points (Figure 1D, 1E, and 1F and Table 1). However, more men in the watchful-waiting group than in the radical-prostatectomy group died from causes other than prostate cancer, but with metastases present (Table 1 and Table 2).
Men with Low-Risk Prostate Cancer
A total of 124 men in the radical-prostatectomy group and 139 in the watchful-waiting group had a PSA level of less than 10 ng per milliliter and a tumor with a Gleason score of less than 7 or a WHO of grade 1 in the preoperative biopsy specimens. Among them, 42 in the radical-prostatectomy group and 68 in the watchful-waiting group died. The 15-year estimates in an intention-to-treat analysis showed that there was an absolute between-group difference of 13.2 percentage points with respect to the rate of death from any cause, corresponding to a relative risk with radical prostatectomy of 0.62 (95% CI, 0.42 to 0.92; P=0.02) (Figure 2Figure 2Cumulative Incidence of Death from Prostate Cancer and Development of Metastases among Men with Low-Risk Prostate Cancer. and Table 1) and a number needed to treat of 8, although with a broad confidence interval. However, 3 of the men in the radical-prostatectomy group did not undergo surgery. With respect to death from prostate cancer, the absolute between-group difference at 15 years was 4.2 percentage points, corresponding to a relative risk of 0.53 (95% CI, 0.24 to 1.14; P=0.14) (Figure 2 and Table 1). The absolute between-group difference with respect to distant metastases was 11.4 percentage points (95% CI, 2.6 to 20.2), corresponding to a relative risk of 0.43 (95% CI, 0.23 to 0.79; P=0.008) (Figure 2 and Table 1). When the Gleason grading of the operative specimens was compared with the preoperative grading of the core biopsy specimens in the 7 men who underwent surgery and died from prostate cancer, the tumors in 6 of the 7 patients were upgraded to a score of 7 or 8 from a score of 6 or lower.
Histopathological Characteristics in the Radical-Prostatectomy Group
Positive surgical margins, which were present in 99 of the 283 prostatectomy specimens that could be evaluated, were associated with a poor prognosis in a model that adjusted only for age. However in a multivariate analysis that included extracapsular tumor growth, PSA level at randomization, and Gleason score, the relative risk associated with positive surgical margins was not significantly increased (data not shown).
Extracapsular tumor growth was found in 132 of the 284 radical-prostatectomy specimens (46%); tumors with extracapsular growth, as compared with those without extracapsular growth, were associated with a risk of death from prostate cancer that was increased by a factor of 7 (relative risk, 6.92; 95% CI, 2.6 to 18.4). Gleason score was also highly predictive of the risk of death from prostate cancer; among 129 men who had tumors with Gleason scores of 2 to 6, only 5 died from prostate cancer (data not shown).
As of the current follow-up analysis, there continues to be a significant reduction in the rate of death from any cause, the rate of death from prostate cancer, and the risk of metastases in the radical-prostatectomy group as compared with the watchful-waiting group. The benefit is obvious among men younger than 65 years of age, but it is still unclear whether the benefit extends to older men. The risk of death from prostate cancer after radical prostatectomy among men who had tumors with extracapsular growth, as compared with men who had tumors without extracapsular growth, was increased by a factor of 7. We also observed a benefit of radical prostatectomy among men with low-risk tumors.
The data on mortality are in accordance with our previous follow-up reports. However, in the current analysis, the number needed to treat to avert one death was 15, as compared with 19 in a previous analysis, in the case of the whole cohort, and the number was 7 in the case of men younger than 65 years of age. A previous analysis indicated that the difference between the two groups remained constant after 9 years. In the current analysis, a continuing benefit with radical prostatectomy was observed also after 9 years of follow-up.
The finding that the effect of radical prostatectomy is modified by age has not been confirmed in other studies of radical prostatectomy or external-beam radiation.11,12 The SPCG-4 data show that men younger than 65 years of age in whom the tumor is left in situ have a worse outcome than do all other subgroups. The apparent lack of effect in men older than 65 years of age should be interpreted with caution because, owing to a lack of power, the subgroup analyses may falsely dismiss differences. At 15 years, there was a trend toward a difference between the two groups in the development of metastases, and more men in the watchful-waiting group than in the radical-prostatectomy group died from causes other than prostate cancer, but with metastases present. Current hormonal treatments might induce remissions long enough for older patients to die from other diseases. Therefore, competing risks of death may blur the long-term effects of treatment, and different classification rules of disease-free survival will influence survival estimates.
The cumulative incidence in our study of death from prostate cancer among men treated with radical prostatectomy was high as compared with the incidence in other studies13,14; nearly 80% of the men enrolled in our study had palpable tumors, with extracapsular tumor growth in 46% of the radical-prostatectomy specimens. All but five men who died of prostate cancer in the radical-prostatectomy group had extracapsular tumor growth. Although extracapsular growth is not a perfect predictor of lethal disease, our findings indicate that these men could be a group for which adjuvant local or systemic therapy would be beneficial.15,16 In studies of active surveillance, a high proportion of patients with extracapsular growth among those who were switched to radical prostatectomy could be an indication that the trigger point for active treatment is too late.
In men with low-risk disease, the absolute benefit of surgery with respect to death from prostate cancer and the risk of metastases was similar to that in the whole cohort. We caution that our low-risk group cannot be compared directly with men who are currently included in active-surveillance protocols because few of the men in our low-risk group had a tumor that was detected by means of a screening test.17,18 Furthermore, the biopsy protocol in this study entails a lower sensitivity for diagnosing high-risk disease than the extensive protocol in a more recent study19; the lower sensitivity in our study is highlighted by the reclassification of the diagnostic Gleason score in the radical-prostatectomy specimens. However, our findings show that some tumors that are considered to be low-risk at diagnosis do pose a threat to life, especially if they are not surgically removed.
The cumulative incidence of side effects of surgery reflects a situation in which, historically, the need for radical excision of the tumor dictated extensive surgery more often than is the case today. Furthermore, the surgical techniques were not as well developed, and the number of surgeries performed was far from today's levels. The data in the current analysis are based on information from medical records. We have previously shown that a complete understanding of the complex balance in effects between surgery and watchful waiting also requires obtaining patient-reported data on the severity of symptoms and on how much the patient is bothered by them.20,21
The strengths of our study include the randomized design, the completeness of follow-up, and the independent and blinded evaluation of the cause of death. Adherence to the assigned treatment was high despite the diversity of the two interventions. Our interpretation relies on stable long-term quantitative estimates, as illustrated in the cumulative-incidence curves and the consistency of the results over an extended follow-up period. The subgroup analyses were not prespecified in the protocol and lack the power to rule out a treatment difference. We emphasize that these results should be interpreted with caution and should be viewed as hypothesis-generating for other studies.
The current analysis adds to our knowledge in several areas. The benefit of radical prostatectomy continued to be seen beyond 9 years, which contradicts the notion that there is only a distinct subpopulation that responds to radical surgery with an early reduction in risk. The accruing numbers of events for the older age group indicate that in our study, a reduction in disease-specific mortality is unlikely ever to become apparent in this age group, owing to competing causes of death. The finding that some low-risk tumors will progress and become lethal emphasizes the importance of protocols with well-defined end points at which men in active surveillance switch to curative treatment. With continued follow-up, data from the SPCG-4 study may allow us to identify prognostic markers in men assigned to watchful waiting that can serve as trigger points for active treatment; the prognostic value of these markers can then be validated in cohorts that are under active surveillance.
Supported by grants from the Swedish Cancer Society (07 0512, to Dr. Johansson) and the National Institutes of Health (1ROI CA 108746-01A1, to Dr. Steineck).
Dr. Spngberg reports serving on the advisory board of Pfizer and receiving lecture fees from Astellas. No other potential conflict of interest relevant to this article was reported.