Trends in poorly differentiated prostate cancer 1973 to 1994: observations from the Surveillance, Epidemiology and End Results database

Abstract

Purpose: Using the Surveillance, Epidemiology and End Results Program, we evaluated the changing demographics of poorly differentiated prostate cancer since early detection measures, such as serum prostate specific antigen screening, were introduced into clinical practice in the United States.

Materials and methods: Trends between 1973 and 1994 in the proportion, stage and treatment of poorly differentiated tumors (International Classification of Diseases [ICD]-O code 3, Gleason score 8, 9, 10) were assessed, and multivariate Cox proportional hazards models were used to identify independent correlates of disease specific survival.

Results: The number of ICD-O grade 3 tumors increased during the study period, although these comprised a decreased proportion of all diagnosed cases (24.4% of 29,588 in 1980 to 1984 versus 21.4% of 81,932 in 1990 to 1994, chi-square p < 0.001). ICD-O grade 3 tumors were less often metastatic in 1990 to 1994 compared to 1980 to 1984 (17.4% versus 33.1%, chi-square p < 0.0001) and more often treated with radical prostatectomy or radiotherapy in 1990 to 1994 compared to 1983 to 1984 (37.5 versus 15.6%, chi-square p < 0.001). Although treatment group (radiotherapy versus radical prostatectomy) among patients with clinically confined tumors was an independent correlate of disease specific survival (hazard ratio 2.3, 1983 to 1984 and 3.3, 1990 to 1994), one must recognize potential selection biases inherent to this nonrandomized tumor registry study. The observed 12-year actuarial disease specific survival rates were 67.6% for radical prostatectomy and 46.3% for radiotherapy.

Conclusions: In the present era ICD-O grade 3 tumors are being detected in increasing number, are less likely to be metastatic at presentation and are more likely to be treated definitively with radical prostatectomy or radiotherapy. Disease specific survival rates observed with radical prostatectomy and radiotherapy in patients with clinically confined tumors support current efforts to detect and treat these highly aggressive tumors while clinically localized.