Outcomes in localized prostate cancer: National Prostate Cancer Register of Sweden follow-up study

Abstract

Background: Treatment for localized prostate cancer remains controversial. To our knowledge, there are no outcome studies from contemporary population-based cohorts that include data on stage, Gleason score, and serum levels of prostate-specific antigen (PSA).

Methods: In the National Prostate Cancer Register of Sweden Follow-up Study, a nationwide cohort, we identified 6849 patients aged 70 years or younger. Inclusion criteria were diagnosis with local clinical stage T1-2 prostate cancer from January 1, 1997, through December 31, 2002, a Gleason score of 7 or less, a serum PSA level of less than 20 ng/mL, and treatment with surveillance (including active surveillance and watchful waiting, n = 2021) or curative intent (including radical prostatectomy, n = 3399, and radiation therapy, n = 1429). Among the 6849 patients, 2686 had low-risk prostate cancer (ie, clinical stage T1, Gleason score 2-6, and serum PSA level of <10 ng/mL). The study cohort was linked to the Cause of Death Register, and cumulative incidence of death from prostate cancer and competing causes was calculated.

Results: For the combination of low- and intermediate-risk prostate cancers, calculated cumulative 10-year prostate cancer-specific mortality was 3.6% (95% confidence interval [CI] = 2.7% to 4.8%) in the surveillance group and 2.7% (95% CI = 2.1% to 3.45) in the curative intent group. For those with low-risk disease, the corresponding values were 2.4% (95% CI = 1.2% to 4.1%) among the 1085 patients in the surveillance group and 0.7% (95% CI = 0.3% to 1.4%) among the 1601 patients in the curative intent group. The 10-year risk of dying from competing causes was 19.2% (95% CI = 17.2% to 21.3%) in the surveillance group and 10.2% (95% CI = 9.0% to 11.4%) in the curative intent group.

Conclusion: A 10-year prostate cancer-specific mortality of 2.4% among patients with low-risk prostate cancer in the surveillance group indicates that surveillance may be a suitable treatment option for many patients with low-risk disease.

Figure 1

Identification and exclusion of men in the National Prostate Cancer Register (NPCR) of Sweden Follow-up Study. The complete database was defined as patients remaining after cleaning of the data set, before exclusion of patients who received hormonal treatment or had poorly differentiated tumors. Data cleaning is exclusion of men with primary treatments other than surveillance, prostatectomy, or radiotherapy; unknown primary treatment; or missing data on PSA, grade, or stage. PSA = prostate-specific antigen; T1x = primary tumor cannot be assessed; WHO = World Health Organization.

Figure 2

Observed and expected all-cause mortality for patients in the National Prostate Cancer Register (NPCR) of Sweden Follow-up Study. A) Patients who were treated with surveillance. B) Patients who were treated with radical prostatectomy. C) Patients who were treated with radiation therapy. Error bars = 95% confidence intervals.

Figure 3

Prostate cancer–specific mortality for patients who were treated with surveillance, radiation therapy, or radical prostatectomy in the National Prostate Cancer Register (NPCR) of Sweden Follow-up Study.A) Combination of low- and intermediate-risk patients. B) Low-risk patients. C) Intermediate-risk patients. Error bars = 95% confidence intervals. RP = radical prostatectomy; RT = radiation therapy; Surv = surveillance.