Biologics Don't Increase Cancer Risks, Two Studies Indicate
“They give you cancer. Stay far away from them.”
This is something you often hear someone say in discussions about treating rheumatoid arthritis (RA) and other chronic illnesses with biologics. When biologics first became available, it was believed there was an association between TNF inhibitors, such as Enbrel, Humira, and Cimzia, and an increased risk of lymphoma, a cancer that develops in the lymphatic system, and other types of cancer. Consequently, the FDA attached a black box warning to these kinds of medications. I should clarify that this was an increase in addition to the already increased risk of lymphoma that is associated with RA, especially severe cases.
Now, two studies from the UK bring good news about biologics, lymphoma, and other types of cancer. The studies used data from the British Society of Rheumatology biologics registry (BSRBR), which was created in 2001 specifically to examine the safety of TNF inhibitors, especially in regard to lymphoma. This gives researchers access to data from a lot of people who take these medications.
TNF inhibitors do not increase risk of lymphoma in RA
The first study compared the risk of lymphoma in people with RA who took TNF inhibitors with those who took non-biologic disease modifying drugs (DMARDs). It examined the records of more than 15,000 individuals, creating a study that was one of the largest comparisons of this risk.
The researchers found that for up to five years after initiating treatment there was no evidence that TNF inhibitors increased the risk of lymphoma above what they called the “background risk” in people who have RA. The conclusion is that disease activity is the primary cause for lymphoma in people with RA.
Another study by Silva-Fernandez et.al. reviewed data from the BSRBR to study the incidence of cancer in people who had RA, as well as a previous diagnosis of cancer. It compared individuals who were taking TNF inhibitors and Rituxan, a biologic targeting B calls, with people who took non-biologic DMARDs.
The reason the researchers included Rituxan was that it has been used as a treatment for B cell lymphoma. Previous studies have included individuals who took both TNF inhibitors and Rituxan, which could therefore affect the findings. The Silva-Fernandez study looked at data from those who took TNF inhibitors, individuals taking Rituxan as their first biologic, and a group taking non-biologic DMARDs.
The study found that there was little difference between the three groups. In addition, they concluded that “after a median follow-up of 6.8 years, there has been no significant increase in the incidence of malignancies in TNF-inhibitor-treated patients.”
As people with RA take biologics for longer periods, more data will be available. That should allow researchers to draw conclusions about lymphoma risk over a longer period of time. As well, I think we will see research into the theory that treatment with biologics could potentially reduce the risk of lymphoma associated with RA by controlling RA inflammation.
On a personal note, I first started taking TNF inhibitors eleven years ago. I was aware of the supposed risk of cancer associated with taking them, but I was in an intense flare that kept getting worse. It was so bad that I had promised myself I’d only have to stick it out for another six months. If a solution hadn’t been found by then, I had given myself permission to commit suicide.
My life was so miserable that the possibility of relief vastly outweighed a small possibility of perhaps developing cancer. The chance to get back my life, even if it was just for a decade, was worth the risk. Many others felt the same way, although for some, the risk was too much.
It is a huge relief to learn that we can now point to studies showing that the risk of lymphoma and other cancers previously thought to be associated with taking certain kinds of biologics is no greater than when taken regular DMARDs or simply having RA. This will make the process of deciding upon a biologic much less scary for those who are about to embark on new treatment. And it does ease that small worry in the back of the minds of those of us who have taken these drugs for a long time.
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