Anti-TNF drugs (otherwise known as tumor necrosis factor-alpha inhibitors) are essential to the treatment of autoimmune diseases such as rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis. These drugs work by supressing the immune system to decrease inflammation and the body’s ability to fight infection. Because of this it was believed that these drugs could increase the risk of certain kinds of cancer, such as lymphoma. New research is challenging this belief.
In the first study, a meta-analysis published in the June 2011 Arthritis & Rheumatism, researchers reviewed six trials that included a total of 2,183 RA patients taking anti-TNFs and 1,236 taking methotrexate. The patients all had early-stage RA and had not been previously treated with methotrexate or other disease-modifying anti-rheumatic drugs, or DMARDs. The duration of the trials were between six and 12 months. The analysis found that 19 people taking at least one dose of an anti-TNF, including adalimumab, or Humira; etanercept, or Enbrel; and infliximab, or Remicade, developed a malignancy compared with 10 patients taking methotrexate. Researchers concluded there was no significant difference in risk.
The second study, presented in May at the 2011 European League Against Rheumatism conference in London, looked at more than 13,600 Danish patients, the majority of whom had RA, from the DANBIO registry, a nationwide database that includes all rheumatic patients receiving biological drugs. From January 2000 to the end of 2008, almost 5,600 of them had started anti-TNF treatment.
The researchers cross-referenced data from DANBIO registry with the Danish Cancer Registry and found that 181 patients ever treated with an anti-TNF developed cancer compared to 132 patients who had not taken an anti-TNF. The researchers concluded there was no statistical difference in cancer risk. After further analyzing the data, the researchers also concluded that the risk of cancer did not rise with longer-term use of anti-TNFs.
Previous research has shown that people with RA, independent of medication use, have a higher risk of cancer than people without the disease. This is possibly due to chronic stimulation of the immune system. Thus the patients who have the most significant disease activity, are more likely to receive anti-TNF agents. These people were more likely to get cancer to begin with.
A 2009 study came to similar conclusions. One of the largest and longest population-based assessments of cancer risks associated with immunosuppressive therapy, published in Arthritis & Rheumatism in 2009, compared cancer rates among more than 75,000 RA patients in Sweden who were taking either no medications, methotrexate, anti-TNF therapies or other DMARDs. In the six-year period they analyzed, the researchers found the risk of developing cancer was the same for people on anti-TNF medications as those in the other groups.
Overall, this is reassuring news to patients. For the vast majority of patients, the benefits of these drugs outweigh the potential risks. They can mean a patient can have an excellent quality of life for years to come.