To investigate serum levels of tumor markers in patients with rheumatoid arthritis (RA) and their association with disease activity or the presence of cancer.
We performed an observational cohort study including 100 patients with RA and control subjects. Serum levels of tumor markers carcinoembryonic antigen (CEA), cancer antigen (CA) 125, CA 19-9 and CA 15-3 were evaluated along with clinical and laboratorial RA data. Association tests between tumor markers levels and RA disease activity parameters were performed. Patients with abnormal tests were submitted to further investigation, including chest X-ray, colonoscopy, abdominal ultrasonography, upper gastrointestinal endoscopy and mammography, depending on the type of tumor marker that was elevated.
Patients with RA had high levels of CEA and CA 19-9 more frequently than controls (P < 0.05). No correlation was found between tumor markers and RA disease activity assessed by the Disease Activity Score 28. Two neoplasms were found, but only one was related to high tumor marker (an ovarian carcinoma with high CA 125 levels).
High tumor markers were frequently found in RA patients, even with controlled disease and were not related to actual cancer. Therefore, small increases of these markers in RA cases probably do not warrant a search for an occult neoplasm.