RA and risk of colorectal cancer: a nationwide cohort study

Abstract

Objective: Prior research on colorectal cancer (CRC) risk in RA lacked analyses incorporating cardiometabolic or behavioural factors, offered limited subsite-specific data and did not consider RA serostatus. This study assessed the association between RA and subsite-specific CRC risk by RA serostatus.

Methods: Using the Korean National Health Insurance System database, we identified 40 909 patients with newly diagnosed RA between 2010 and 2017, matched by age and sex at a 1:5 ratio with 204 545 non-RA participants. Multivariable Cox regression models were used to estimate hazard ratio (HR) for the association between RA and CRC incidence.

Results: During a median follow-up of 5.3 years, 2174 subjects (319 with RA and 1855 controls) were diagnosed with CRC. Patients with RA had a decreased risk for CRC compared with non-RA participants (HR, 0.89; 95% CI, 0.79-0.99). A decreased risk of CRC was found in patients with seronegative RA (HR, 0.79; 95% CI, 0.63-0.98) but not in those with seropositive RA (HR, 0.93; 95% CI, 0.81-1.06). The inverse association between RA and CRC was significant for rectal cancer (HR, 0.63; 95% CI, 0.45-0.87) but not for proximal (HR, 1.04; 95% CI, 0.79-1.39) or distal colon cancer (HR, 0.84; 95% CI, 0.64-1.11). The inverse association between RA and CRC risk was more pronounced in women (HR, 0.80; 95% CI, 0.69-0.94; P for interaction = 0.043).

Conclusions: Our analyses provide solid evidence of an inverse association between RA and CRC risk, particularly in patients with seronegative RA, rectal cancer cases and women.

Keywords: RA; colorectal cancer; seronegative RA; seropositive RA.