Risk of malignancy among patients with rheumatic conditions

Previous studies have described an increased risk of malignancy in subjects diagnosed with rheumatic conditions, most notably rheumatoid arthritis (RA ). Our aim was to quantify and compare risks for site-specific malignancy a mong hospitalized patients with RA, osteoarthritis (OA) and other rheumatic conditions in a nationwide, population-based cohort. Subjects were identif ied from Scottish hospital in-patient records from 1981 to 1996 and followe d up by computer linkage of the Scottish Cancer Registry and the national r egistry of deaths. Expected cancer incidence was calculated from national c ancer rates and related to the observed incidence by the standardized incid ence ratio (SIR). Among RA patients, there was an increased risk for hemato poietic [males SIR = 2.13, 95% confidence interval (CI) 1.7-2.7; females SI R = 1.76, 95% CI 1.5-2.1], lung (males SIR = 1.32, 95% CI 1.2-1.5; females SIR = 1.44, 95% CI 1.3-1.6) and prostate (SIR = 1.26, 95% CI 1.0-1.6) cance rs. Reduced risk were seen for colorectal cancer (males SIR = 0.87, 95% CI 0.7-1.1; females SIR = 0.71, 95% CI 0.6-0.9) and, among females, stomach ca ncer (SIR = 0.70, 95% CI 0.5-1.0). The excess risk for hematopoietic cancer and the reduced risk for colorectal and stomach cancers were sustained ove r 10 years of follow-up. An overall decreased risk of cancer was observed f or patients with OA; the greatest reductions were observed for colorectal ( males SIR = 0.88, 95% CI 0.8-1.0; females SIR = 0.84, 95% CI 0.8-0.9), stom ach (males SIR = 0.79, 95% CI 0.7-0.9; females SIR = 0.66, 95% CI 0.6-0.8) and lung (males SIR = 0.72, 95% CI 0.7-0.8; females SIR = 0.84, 95% CI 0.8- 0.9) malignancies, with decreased risks generally still evident at 10 years of follow-up. Our results support several previous findings regarding the incidence of hematopoietic and colorectal malignancies in RA patients. In a ddition, we have shown a large decrease in stomach cancer among patients wi th OA and females with RA that warrants further investigation since it: may provide clues to possible prevention strategies. To further our knowledge about the underlying mechanisms of altered risk in cancer patients with rhe umatic conditions, population studies requiring primary data collection are required. Int. J. Cancer 88:497-502, 2000. (C) 2000 Wiley-Liss, Inc.