medwireNews: Findings from the ARTIS study group suggest that biologic disease-modifying antirheumatic drugs (bDMARDs) and tumor necrosis factor (TNF) inhibitors are not associated with an increased overall cancer risk compared with conventional synthetic (cs)DMARDs.
“Because immune suppression may lower a host’s surveillance against developing tumors monitoring cancer incidence is an important aspect of the safety of biologics used in rheumatology,” commented Hjalmar Wadström (Karolinska Institute of Stockholm, Sweden) in a press statement at the Annual European Congress of Rheumatology (EULAR) 2017 in Madrid, Spain.
“Our data should be reassuring bearing in mind the widespread current use of anti-TNF drugs to treat RA,” he said, and the fact that “previously we knew a lot less about the cancer risk with other bDMARDS.”
The team assembled six cohorts of patients with RA from the Swedish Patient Register. These included 1798, 2021, and 3586 patients taking tocilizumab, abatacept, or rituximab treatment, respectively, 10,782 patients receiving TNF inhibitors as their first bDMARD, 4347 receiving TNF inhibitors as a second bDMARD, and a csDMARD treatment group consisting of 46,610 patients who were biologic-naïve. All the patients were matched 1:5 to a total general population cohort of 107,491 individuals for age, gender, and residency.
Patients receiving biologics were no more likely than those taking csDMARDs to develop a first solid or hematologic malignancy, excluding non-melanoma skin cancer, between the start of treatment and the end of December 2015.
There were 50 events among patients taking tocilizumab, 61 events among those taking abatacept, and 141 events among rituximab-treated patients. And after adjusting for a range of factors, including age, gender, education, comorbidities, seropositivity, hospital use, inpatient-care, and the use of prednisolone and nonsteroidal anti-inflammatory drugs, there was no statistically significant difference in the risk for cancer for these patients compared with those taking csDMARDs.
Likewise, Wadström said that based on 478 events among patients treated with TNF inhibitors as their first biologic and 169 among those treated with TNF inhibitors as their second biologic, there was no statistically significant risk difference compared with patients treated with csDMARDs.
“There was, however, a significantly lower risk among the general population compared to csDMARD-treated patients,” he noted.
Analyses of the secondary outcomes, for which Wadström pointed out there was “a lot less power,” showed that among 125 tests comparing different biologic groups with csDMARD treatment, there was a significantly higher risk for first-ever squamous cell skin cancer among the abatacept-treated patients, with a fully adjusted hazard ratio of 2.2.
“We think the finding of an increased risk of squamous cell skin cancer should be interpreted cautiously; seeing how many tests were performed this could be down to simply multiple testing, it could also be caused by bias, but of course it can’t be just disregarded and needs to be further studied and replicated,” said Wadström.
He concluded: “This study confirms previous findings of no increased risk of overall cancer with TNF inhibitor treatment, neither as a first or a second biologic. Also, for tocilizumab, abatacept, and rituximab, this study showed no increased risk of overall cancer.”
Complementary research from a second presentation at the conference by the same study group showed that TNF-inhibitor treatment does not increase the risk for recurrence relative to other treatments in RA patients with a history of cancer.
Among 446 patients with at least one prior diagnosis of a solid cancer who started TNF-inhibitor therapy and 1278 patients with a history of equally recent cancer and stage who were not prescribed biologic therapy, approximately 7% in each group had a recurrence over 4.9 and 4.1 years of follow-up, respectively.
This gave a crude incidence rate of 14 events per 1000 person–years for patients treated with a TNF inhibitor and 17 per 1000 person–years for patients who were not.
Statistical analysis adjusting for gender, year of diagnosis of the index cancer, index cancer type and stage, education, and comorbidities showed no increased risk for recurrence of any specific cancer type.
The only possible exception was uterine cancer, which had a hazard ratio for recurrence of 14.8 in TNF inhibitor-treated patients, but Akling noted that this was based on a single event.
He also pointed out in a press statement that the risk for recurrence did not vary depending on the timing of TNF-inhibitor initiation in relation to the original cancer diagnosis.
Akling echoed Wadström’s comment that rheumatologists should be reassured by the findings, particularly as “current guidelines do not provide clear guidance regarding the use of anti-TNF treatment in patients with recent malignancies.”
However, he cautioned that “it is not possible to extrapolate these new findings to individuals with a very recent cancer, or a poor prognosis.”
By Lucy Piper
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