Risk of kidney cancer and other second solid malignancies in patients with chronic lymphocytic leukemia.

Patients with chronic lymphocytic leukemia (CLL) are known to to have an increased incidence of secondary cancers. We investigated the occurrence of secondary cancers in 7391 patients with CLL diagnosed between 1955 and 1988. The observed number of cancer cases was compared with the expected number of cancers calculated from national cancer incidence rates. The overall risk of cancer was significantly increased among persons with CLL. The standardized incidence ratios (ratio between the observed and the expected numbers) were 2.0 for men and 1.2 for women. Increased risks were found for cancer of the lung and prostate in men (RR = 2.0 and 1.5 respectively), renal parenchyma in both sexes (RR = 2.8 for men, RR = 3.6 for women) non-melanoma skin cancer in both sexes (RR = 4.7 for men, RR = 2.4 for women) and sarcomas (RR = 3.3 for men, RR = 2.8 for women). Although an increased risk of cancer is to be expected solely because individuals with CLL are being physically examined frequently, it appears that the risk is significantly increased for a number of cancer sites in persons with CLL.