TNF has both tumor-promoting and cancer-protective effects, so TNF inhibitors could conceivably affect the risk for cancer recurrence. However, few studies have reported the risk for cancer relapse or second primary tumors in patients with RA who received TNF inhibitor treatment.
Pauline Raaschou, MD, PhD, from Karolinska Institutet, Stockholm, and colleagues used data from linked Swedish registries to compare cancer recurrences in RA patients who had started TNF inhibitor treatment after their cancer diagnosis vs. those who remained biologics-naive.
The first, most inclusive comparison matched 467 patients who started TNF inhibitor treatment between 2001 and 2015 after a cancer diagnosis an average of eight years earlier and 2,164 biologics-naive patients with a history of cancer. During a mean 5.3 years of follow-up in the TNF inhibitor group and 4.3 years in the comparison group, recurrence rates did not differ significantly between the groups (9.0% vs. 7.2%, respectively).
After restricting the groups to patients whose cancer was diagnosed in 2001 or later, there was still no significant difference in recurrence rates (10% of those treated with TNF inhibitors vs. 7.3%), the researchers report in the Aug. 14 issue of Annals of Internal Medicine.1
In the most restrictive matched analysis (patients whose index cancer occurred in 2003 or later), the risk of cancer recurrence remained similar in patients treated with and without TNF inhibitors.
Finally, cancer recurrence rates did not differ significantly between the groups in an unmatched analysis.
“Our findings suggest that TNF inhibitor treatment was not associated with an increased risk for cancer recurrence in patients with RA and a history of cancer compared with those who had a similar cancer history and were selected to receive other RA treatments,” the researchers conclude. “However, as suggested by the upper limit of the confidence interval for several risk estimates, a clinically meaningful risk cannot be completely ruled out.”
They add, “Our results should be interpreted in light of the treatment channeling that is part of clinical practice and may not be directly applicable to patients with ongoing cancer or a recent cancer diagnosis or to all cancer types.”
Dr. Kimme Hyrich from The University of Manchester’s Arthritis Research U.K. Center for Epidemiology, in the U.K., who earlier reported that TNF inhibitors did not appear to increase cancer-recurrence rates in U.K. RA patients, tells Reuters Health by email the new results “add to the reassuring data that a past history of cancer is not an absolute contraindication for future TNF inhibitor therapies.”