PROSTATE-CANCER IN ROCHESTER, MINNESOTA (USA), FROM 1935 TO 1989 - INCREASES IN INCIDENCE RELATED TO MORE COMPLETE ASCERTAINMENT

Prostate cancer incidence among White men in the United States climbed steadily from 45 per 10(5) person-years (PY) during 1945-54 to 102 pe r 10(5) PYs in 1988. To determine whether this increase might be the r esult of changing diagnostic practices, we examined trends in incidenc e and method of diagnosis in Rochester, Minnesota (US), from 1935 to 1 989. We found a parallel increase in Rochester in non-autopsy diagnose s from 44 (95 percent confidence interval [CI] = 29-58) cases per 10(5 ) PYs in 1935-44 to 71 (CI = 52-89) cases per 10(5) PYs in 1985-87 whi ch was driven by diagnoses prompted by digital rectal examination. The re was no evidence that an increasing proportion of cases was found as the result of procedures to treat the symptoms of benign prostatic hy perplasia. Including autopsy diagnoses, incidence was stable over this extended interval and was 77 per 10(5) PYs (CI = 58-97) in 1935-44 an d 72 per 10(5) PYs (CI = 53-91) in 1985-87. Incidence more than double d after introduction of diagnostic serum prostate-specific antigen (PS A) assay and was 179 per 10(5) PYs (CI = 145-214) in 1988-89. We concl ude that prostate-cancer incidence rates are influenced strongly by di agnostic practices and that national increases could reflect, to a lar ge extent, more complete and earlier ascertainment rather than more fr equent disease.