MADRID – Biologics and tumor necrosis factor–inhibitors confer very little – if any – risk of malignancy upon those who take them for rheumatoid arthritis, according to a large Swedish registry study.
A doubling in the risk of squamous cell carcinoma among those who took abatacept was the only significant finding in the 8-year study of almost 70,000 subjects, Hjalmar Wadstrom, said at the European Congress of Rheumatology. And while he said the finding could be spurious, he stressed that it can’t be ignored.
“We think this finding should be interpreted cautiously,” said Mr. Wadstrom, a doctoral student at the Karolinska Institute, Stockholm. “These patients are seen frequently, and this increase in sqaumous cell carcinoma could be related to this multiple screening, or due to study bias. But of course, we cannot disregard it. It should be validated and further examined.”
The study plumbed several national patient registries and administrative databases for its cohort. It comprised 22,500 patients who, from 2006 to 2014, took tocilizumab, abatacept, or rituximab; or a TNF-inhibitor as a first or second disease-modifying antirheumatic drug. These were compared to 46,600 patients who took synthetic DMARDS during the same period and to a matched general population cohort (107,500). The mean age of all groups was about 59 years.
The primary outcome was a first-ever solid or hematologic malignancy excluding nonmelanoma skin cancer. The fully adjusted risk model controlled for age, sex, educational level, comorbidities, seropositivity, number of hospitalizations and days spent in inpatient care, use of prednisone at baseline, use of nonsteroidal anti-inflammatory drugs at baseline, number of prescription drugs at baseline, and sick leave and disability.
A first invasive solid tumor or hematologic malignancy occurred in 50 patients taking tocilizumab; 61 taking abatacept; 141 taking rituximab; 478 taking a TNF-inhibitor as the first biologic DMARD; and 169 taking a TNF-inhibitor as the second DMARD. There was no statistically significant difference between any of these groups, when they were compared either to each other, to those taking a conventional synthetic DMARD, or to the general population.
The doubled risk of squamous cell carcinoma associated with abatacept (HR 2.2) was the only significant positive finding the secondary analysis, Dr. Wadstrom said.
He had no financial disclosures.
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