Cancer risk in a cohort of polio patients

Poliomyelitis has hypothetically been associated with an increased risk of central nervous system (CNS) tumors. The present study was performed to exa mine not only the risk of CNS tumors but also the overall risk of cancer am ong a cohort of 5,883 polio patients. Patients diagnosed with acute poliomy elitis in the Danish capital, Copenhagen, between 1919 and 1954 were identi fied and followed with respect to cancer. Information on vital status and c ancer diagnoses was obtained through linkage with the Danish Civil Registra tion System and the Danish Cancer Registry, respectively. The ratio of obse rved number of cancers to the number expected from population-based inciden ce rates, i.e., the standardized incidence ratio (SIR), sewed as measure of the relative cancer risk. Overall, 717 cases of cancer were observed among 5,883 polio patients during 249,084 person-years of follow-up vs. an expec ted number of 645 (SIR 1.11 [95% confidence interval 1.03 to 1.20]). The in creased risk was restricted to female polio patients (SIR = 1.18 [1.07 to 1 .30]), among whom the risk was particularly high for breast cancer (SIR = 1 .35 [1.12 to 1.61]) and for skin cancer (SIR = 1.66 [1.32 to 2.07]). The ri sk of breast cancer was highest among women with a history of paralytic pol io (SIR = 1.62 [1.24 to 2.10]), The observed number of CNS tumors did not e xceed the expected (SIR 1.09 [0.72 to 1.60]). Women diagnosed with poliomye litis, in particular paralytic polio, may be at increased risk of breast ca ncer. There was no association between malignancies of the CNS and poliomye litis. (C) 2001 Wiley-Liss, Inc.