A sigh of relief for many Chron’s and colitis patients: the class of drugs known as tumor necrosis factor alpha (TNF-a) antagonists do not cause an short-term increased risk of cancer. The findings originate from a study authored by Dr. Nynne Nyboe Andersen at the Statens Serum Institute in Copenhagen and published in the Journal of the American Medical Association.
Anti-TNF-a drugs include adalimumab (Humira), certolizumab (Cimzia), etanercept (Enbrel), gloimumab (Simponi), and infliximab (Remicade). “These results did not reveal any significantly increased risk of cancer,” said Dr. Andersen. Cancer occurred in just under 2% of patients treated with TNF-a antagonists, and nearly 7% of patients not treated with anti-TNF-a drugs developed cancer.
The study authors were interested in a possible association between TNF-a antagonists, which interrupt the inflammation response of the immune system, and cancer. “Treatment with these drugs inhibits the inflammatory response in the gastrointestinal tract thereby leading to reduced symptoms [of inflammatory bowl disease],” said Dr. Andersen. TNF-a antagonists are suspected of allowing cancer progression because “[TNF-a] is one of the actual bullets that the immune system uses to shoot down and kill cancer cells or a cell that is infected by a bacteria or a virus,” said Fadi Braiteh, from Comprehensive Cancer Centers of Nevada. “By cooling down the immune system, you can improve the ability of cancer cells to escape detection and develop into full-blown cancer.”
Their reasoning was not unfounded: an analysis from 2006 of early clinical trials showed a threefold increase in cancer risk among patients. However, subsequent analyses could not confirm the same results.
Dr. Andersen’s study looked at cancer rates of more than 56,000 inflammatory bowel disease patients and compared the anti-TNF-a patients (8.1% of the total) with the non-anti-TNF-a patients. The average follow-up for patients was 3.7 years, meaning the results may not apply to long-term cancer risk.
A tradeoff between cancer risks may negate the risks specific to anti-TNF-a. According to Dr. Braiteh, cooling down the immune system to prevent constant colon inflammation may reduce the risk of colon cancer but may potentially increase the risk of developing another form of cancer. “We may be decreasing your risk of colon cancer, but slightly increasing your risk of other cancers, so the net balance is zero,” said Dr. Braiteh. “Maybe we’re trading a risk of colon cancer for other cancers but the net balance is even.”
Further research is warranted to confirm the team’s findings. If patients and healthcare providers are hesitant about anti-TNF-a medications, alternatives exist, such as methotrexate, although they may not be as effective and may carry the same autoimmune-related cancer risk. However, Dr. Braiteh affirms, “This study is comforting for patients and doctors who treat these patients for an inflammatory bowel disease that increases your risk of colon cancer to start with.” Inflammatory bowel disease patients should therefore continue on their anti-TNF-a medications without concern for cancer.
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