Phenacetin and papillary necrosis: independent risk factors for renal pelvic cancer.

A case-control study was undertaken to determine whether renal papillary necrosis (RPN) is an essential step in the genesis of analgesic-associated cancer of the renal pelvis (CaP). Kidneys of 66 patients (and 86 cases of renal parenchymal cancer (CaK), for comparison) were examined for evidence of RPN. Information concerning past consumption of phenacetin-containing analgesics (PhA) was obtained from all cases and 751 population controls by means of a questionnaire. Separately, RPN and regular consumption of PhA each conferred a relative risk for CaP of 3-1/2 to 7, while together they increased the risk some 20 times that for non-consumers without RPN. This suggests that each factor has independent, and when they coexist sequential, effects. The risk for CaK was doubled by regular PhA consumption but was not increased by RPN.