STOCKHOLM, Sweden—Data on the first 6 years of anti-TNF therapy in routine care of rheumatoid arthritis (RA) patients show no increase in cancer risk, and this safety level was maintained throughout continued follow-up, Swedish researchers report in Arthritis and Rheumatism.1

“We conclude that the overall occurrence of cancer during the first years following anti-TNF therapy in RA is not higher than that in biologics-naive patients with RA, nor does it increase with time.”—Johan Askling, MD, PhD
The analysis included 25,693 person-years of follow-up in 6,366 patients. During that time, 240 first cancers occurred, yielding a relative risk (RR) of 1.0 versus the biologics-naive RA cohort.

“We conclude that the overall occurrence of cancer during the first years following anti-TNF therapy in RA is not higher than that in biologics-naive patients with RA, nor does it increase with time,” said lead author Johan Askling, MD, PhD, of the Clinical Epidemiology Unit at Karolinska University Hospital in Stockholm. “During the first year of follow-up, but not thereafter, the 3 anti-TNF agents displayed somewhat different cancer risks, the reason for which is unclear. At present, and given the remaining uncertainties, continued vigilance remains prudent.“

Table 1. Relative risk of first primary cancer in RA patients receiving anti-TNF therapy, vs. biologics-naive RA patients
  Etanercept
n=2216		 Infliximab
n=3249		 Adalimumab
n=899		 P
Overall 0.78 1.09 1.32 0.03
<1 yr of anti-TNF 0.43 1.23 1.91 0.00
1-2 yrs of anti-TNF 0.80 0.83 0.84 0.99
>2yrs of anti-TNF 0.92 1.13 1.08 0.53


The researchers also compared relative risk of cancer in RA patients receiving anti-TNF therapy to those newly starting methotrexate (MTX). This showed an RR of 0.99.

When effects of individual anti-TNF agents were analyzed, the investigators found that first starters of etanercept had a lower risk of cancer during the first year of follow-up, as compared with biologics-naive RA patients, while patients first starting adalimumab were at increased risk. These differences disappeared during the second year of follow-up.

Reference

1. Askling J, van Vollenhoven RF, Granath F, et al. Cancer risk in patients with rheumatoid arthritis treated with anti-tumor necrosis factor α therapies. Does the risk change with the time since start of treatment? Arthritis Rheum 2009;60:3180-3189.