Risk of cancer among rheumatoid arthritis patients in California.
OBJECTIVE
The objective of this retrospective cohort study was to evaluate cancer risk among rheumatoid arthritis (RA) patients in California.


METHODS
The study cohort derived from statewide patient discharge records was followed via linkage with cancer registry data over the period 1991-2002. Age and sex adjusted standardized incidence ratios (SIRs) and 95% confidence intervals were calculated to compare observed to expected numbers of cancers based on age, race, and sex specific incidence rates in the California population.


RESULTS
Among the 84,475 RA patients, who were observed for 405,540 person-years, 5,533 incident cancers were diagnosed during the observation interval. The risk of developing lymphohematopoietic cancer was significantly higher in the cohort for both sexes. Males had significantly higher risks of lung, liver, and esophageal cancer, but a lower risk of prostate cancer. Females were at significantly decreased risk for several cancers including breast, ovary, uterus, cervix, and melanoma, with the risk reduction ranging from 15 to 57% lower than the general population. Hispanics had increased risks of leukemia, vagina/vulva, lung, and liver cancers.


CONCLUSIONS
Studies investigating the mechanisms that underlie the reported associations between RA and specific cancer types are needed.
Parikh-Patel
Arti
A
California Cancer Registry, Public Health Institute, 1825 Bell Street, Suite 102, Sacramento, CA 95825, USA. aparikh@ccr.ca.gov
White
Richard H
RH
Allen
Mark
M
Cress
Rosemary
R
D017677:Age Distribution; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000453:epidemiology*; D002140:California / Q000453:epidemiology; D015331:Cohort Studies; D005006:Ethnicity; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008498:Medical Record Linkage; D009369:Neoplasms / Q000453:epidemiology* / Q000209:etiology; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D013997:Time Factors