A systematic review published in the Annals of the Rheumatic Diseases suggests, that biological agents used for the treatment of rheumatoid arthritis seem to be linked with an increased risk of skin cancer. Inflammatory arthritis has been associated with an increased risk of some types of cancers, in particular with lymphoma and lung cancer but with a lower risk of other cancer types, such as bowel and breast cancers.

Researchers set out to clarify whether tumor necrosis factor (TNF) inhibitors, i.e. drugs acting on the immune system, might affect the risk of cancer, by evaluating several clinical research databases, findings presented to the American College of Rheumatology, the European League against Rheumatism, and the British Society for Rheumatology between 1998 and 2010.

The findings were based on 21 studies and 8 conference abstracts, all complying to the strict inclusion criteria of reporting data on cancer linked to TNF inhibitors, including the monoclonal antibodies infliximab and adalimumab and the protein etanercept. In total researchers collated information on over 40,000 patients and nearly 150,000 cumulative years of exposure to these drugs.

The combined risk from seven studies for the development of any cancer revealed negligible or no increased risk, overall.

Two studies also showed no evidence of an increased cancer risk in patients taking TNF inhibitors over long-term, however, those previously diagnosed with cancer had a higher chance of being re-diagnosed with the disease, although this was not due to using TNF inhibitors.

Four studies revealed that patients treated with TNF inhibitors had a 45% higher chance of developing skin cancer other than melanoma, whereas two studies showed, that patients taking TNF inhibitors had a 79% increased risk of developing a melanoma compared with those who did not take these drugs.

The authors conclude:

“This systematic review and meta analysis provides reassurance to physicians and patients that the treatment of [rheumatoid arthritis] with TNF inhibitors does not increase the risk of malignancy, particularly lymphoma. However, it does appear to increase the risk of skin cancer, including melanoma.”

Written by Petra Rattue