Objectives: Age and pathologic grade are 2 critical factors used to guide clinical decisions and comparative outcomes studies in prostate cancer. The objective of this investigation was to use the Surveillance, Epidemiology, and End Results (SEER) registry to examine time trends in age and grade.
Methods: The SEER public-use registry was queried by year of diagnosis from 1974 to 2003 for age at diagnosis (40-49, 50-59, 60-69, 70-79, and 80+ years) and for pathologic grade [well differentiated (WD), moderately differentiated (MD), and poorly differentiated (PD) disease]. Results were tabulated by 5-year interval; a total of 455,170 patients were included in the analysis. Time-trends analyses were performed for age, for grade, and for age and grade simultaneously, in each case applying a multivariate chi test. Five-year cause specific survival (CSS) rates were also tabulated by age and grade.
Results: Overall, there was a nonsignificant (P = 0.68) change in distribution of age at diagnosis. However, a significant (P < 0.001) grade migration took place over the study period, principally from WD to MD disease, and occurred across all age groups. Five-year cause specific survival time trends were similar for all age groups, but WD appeared to converge with MD disease in later years.
Conclusions: An overall grade migration has occurred in prostate cancer, primarily observed as a shift from WD to MD disease; this may weaken grade-based prognostic categorizations. This migration occurred independent of patient age, reinforcing that the grade migration is likely due to changes in pathologic interpretation rather than to screening-related changes in disease characteristics.