Natural experiment examining impact of aggressive screening and treatment on prostate cancer mortality in two fixed cohorts from Seattle area and Connecticut

Abstract

Objective: To determine whether the more intensive screening and treatment for prostate cancer in the Seattle-Puget Sound area in 1987-90 led to lower mortality from prostate cancer than in Connecticut.

Design: Natural experiment comparing two fixed cohorts from 1987 to 1997.

Setting: Seattle-Puget Sound and Connecticut surveillance, epidemiology, and end results areas.

Participants: Population based cohorts of male Medicare beneficiaries aged 65-79 drawn from the Seattle (n=94 900) and Connecticut (n=120 621) areas.

Main outcome measures: Rates of screening for prostate cancer, treatment with radical prostatectomy and external beam radiotherapy, and prostate cancer specific mortality.

Results: The prostate specific antigen testing rate in Seattle was 5.39 (95% confidence interval 4.76 to 6.11) times that of Connecticut, and the prostate biopsy rate was 2.20 (1.81 to 2.68) times that of Connecticut during 1987-90. The 10 year cumulative incidences of radical prostatectomy and external beam radiotherapy up to 1996 were 2.7% and 3.9% for Seattle cohort members compared with 0.5% and 3.1% for Connecticut cohort members. The adjusted rate ratio of prostate cancer mortality up to 1997 was 1.03 (0.95 to 1.11) in Seattle compared with Connecticut.

Conclusion: More intensive screening for prostate cancer and treatment with radical prostatectomy and external beam radiotherapy among Medicare beneficiaries in the Seattle area than in the Connecticut area was not associated with lower prostate cancer specific mortality over 11 years of follow up.

Figure 1

Unadjusted cumulative incidence of a first prostate specific antigen test for study cohort members in the Seattle-Puget Sound and Connecticut areas, 1988-93

Figure 2

Unadjusted 10 year cumulative incidence of prostate cancer for study cohort members in the Seattle-Puget Sound and Connecticut areas, 1987-96

Figure 3

Unadjusted 10 year cumulative incidence of radical prostatectomy (top) and external beam radiotherapy (bottom) for cohort members in the Seattle-Puget Sound and Connecticut areas, 1987-96

Figure 4

Age adjusted prostate cancer mortality per 100 000 person years for men in Seattle-Puget Sound and Connecticut on the basis of cross sectional data, 1987-97 (adjusted to the age composition of the entire study cohort: 48.3% aged 70-74, 33.3% aged 75-79, 18.4% aged 80-84 as of 1 January 1992). (US data by SEER region, age, and race provided by L Ries, Cancer Statistics Branch, National Cancer Institute)