Prostate Cancer Risk and in U.S. Veterans with Rheumatoid Arthritis

Patients with rheumatoid arthritis (RA) have been shown to have an increased risk of some cancers, but its impact on prostate cancer risk is unclear, according to Austin M. Wheeler and collaborating researchers. The team examined a cohort of patients in the Veterans Health Administration (VA) and reported that “RA was associated with a modestly increased risk of prostate cancer, but not prostate cancer mortality, after accounting for relevant confounders and several potential sources of bias.”

The study analyses, published in Arthritis Care & Research, reviewed 1:5 matched cohorts of 56,514 veterans with RA and 227,284 without RA from 2000 to 2018. Investigators identified prostate cancer cases via linked VA cancer databases and the National Death Index. The analyses utilized multivariable Cox regression models to compare risk between RA and non-RA with adjustments for subject retention in the VA system.

Prostate Cancer Risk and Rheumatoid Arthritis Association Findings

In the combined 2,337,104 patient-years of follow-up, the authors observed 6,550 cases of prostate cancer. The overall prostate cancer incidence was 3.50 per 1,000 patient years in the RA cohort (95% confidence interval [CI], 3.32–3.69) and 2.66 in non-RA (95% CI, 2.58–2.73). After performing adjusted analyses, the investigators reported that RA was modestly associated with an increased risk for prostate cancer (hazard ratio [HR] =1.12; 95% CI, 1.04–1.20).

Overall, the authors attributed a modestly increased risk for prostate cancer to patients with RA, consistent with associations between RA and other types of cancer. Regarding the lack of an apparent association between RA and prostate cancer mortality, the authors suggested that “even minimal unmeasured confounding could explain these findings.”

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