Cancer risk not increased by anti-TNF therapy
Cancer risk is not increased during the first six years after starting anti-tumour necrosis factor (anti-TNF) alpha treatment in patients with rheumatoid arthritis (RA), a new study indicates (Arthritis & Rheumatism 2009;60:3180).
Researchers based in Sweden examined the short- and medium-term cancer risk for 6,366 patients using infliximab, adalimumab or etanercept, comparing the incidence of new cancers diagnosed among these patients with other groups of RA patients (see Panel).
The researchers found that the relative risk of developing cancer did not increase or decrease with increasing time since the start of anti-TNF therapy, nor did it increase with the cumulative duration of active anti-TNF therapy.
When considering the three anti-TNF therapies separately, none was associated with an increased overall risk of cancer. However, differing risks were observed during the first year of follow-up (users of etanercept had a lower cancer risk than those RA patients who were anti-TNF naive, whereas adalimumab users were at an increased risk).
The researchers state: “The effect of an anti-TNF agent on cancers seen during an early stage of therapy might be due to existing preclinical tumours becoming clinically manifest, either by allowing more actual tumour growth or by influencing the development of clinical symptoms as a result of the presence of the cancer, rather than being due to the occurrence of a new cancer.”
They add that patients receiving anti-TNF therapy have a cancer risk similar to RA patients who have not received such therapy, patients starting methotrexate and patients starting with a nonbiological disease-modifying antirheumatic drug combination therapy.
Data for 6,366 patients receiving anti-TNF therapy, followed for the equivalent of 25,693 person-years, were compared with those for 61,660 anti-TNF naive RA patients (330,498 person-years), 5,989 patients starting methotrexate therapy (23,558 person-years) and 1,838 patients starting non-biological disease-modifying antirheumatic drugs (DMARD) combination therapy (7,043 person-years).
The relative risk (RR) of a first primary cancer occurring in the anti-TNF group (240 cancers) compared with an anti-TNF naive RA patient (4,244 cancers) was 1.00 (95 per cent confidence interval 0.87–1.17).
This risk did not change with increasing duration of anti-TNF therapy (RR 0.96, CI 0.50–1.86, for those with six years or more anti-TNF therapy).
The RR compared with the methotrexate group, where 260 cancers occurred, was 0.99 (CI 0.79–1.24).
The RR compared with the DMARD group, where 64 cancers occurred, was 0.97 (CI 0.69–1.36).
Citation: The Pharmaceutical Journal URI: 10984630
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