When compared to the general population, it appears that people living with rheumatoid arthritis are at a greater risk for various types of cancer.
The findings from a variety of studies over the years found that the overall risk for cancer seems to be higher among people with rheumatoid arthritis (RA) compared to people without the disease.
Experts say this heightened susceptibility toward getting cancer has to do with a variety of factors, including genetics, lifestyle, and which medications are being used to treat the RA.
It’s worth noting that a greater risk for malignancy isn’t the only RA-cancer link. Some medications used to treat RA also bring on cancer, and vice versa.
According to the recent findings, people with RA were also actually less likely to have certain types of cancer. However, when they did get those forms of cancer, the symptoms were often worse.
For example, there’s an overall reduced risk for breast cancer as well as gastrointestinal, liver, and colon cancers among people with RA. However, there’s a worse outlook associated with these kinds of cancers in these individuals.
There’s a 40 percent higher death rate among people with RA and breast cancer, compared to people with breast cancer but no RA.
Other cancer links
There have been other links noted between cancer and RA.
For people with both RA and squamous cell carcinoma, hematopoietic malignancies, or cancers of the upper aerodigestive tract and prostate, their outlook and mortality were both worse, according to a study published in December.
People who had RA along with prostate cancer had a 50 percent higher death rate than those who had prostate cancer but not RA.
The study also noted that people with RA have been shown to have an increased incidence of lung cancer with a worse outlook and a notably increased risk for lymphoproliferative malignancies, including Hodgkin and non-Hodgkin’s lymphoma.
However, people who had both RA and non-Hodgkin’s lymphoma had similar survival rates to people with this type of lymphoma from within the general population.
There’s some evidence that RA medications can cause an increased risk for cancer, even though some of the treatments for RA and cancer may occasionally overlap.
Some data suggests that disease-modifying antirheumatic drugs (DMARDs) may increase the risk for cancer.
More specifically, it seems that certain traditional DMARDs may increase the risk for specific associated cancers. Azathioprine has been linked with an increased risk for lymphoproliferative disorders and other malignancies in people with RA, while cyclophosphamide seems to increase the risk for hematologic malignancies, urinary tract and bladder cancers, and others.
Some intravenous or injectable biologic drugs also warn of increased risks for certain cancers, such as lymphomas, when listing side effects. These drugs includes anti-TNF agents, JAK inhibitors, and B-cell inhibitors.
The challenge for medical professionals
This apparent risk between the therapies used to manage RA and potential increased malignancy could present a significant challenge to researchers and doctors.
People with RA have an increased risk for lymphoma and lung cancer, compared with the general population.
However, “this risk appears to be related to having RA itself, rather than with the use of biologic medications, as recent large studies have shown,” Dr. Laura Cappelli, MHS, assistant professor of medicine in the division of rheumatology at Johns Hopkins School of Medicine in Maryland, told Rheumatology Advisor.
Another rheumatologist, Dr. Eric L. Matteson, MPH, chair of rheumatology and professor of medicine at the Mayo Clinic in Minnesota, told Rheumatology Advisor: “RA is associated with a greater than twofold increased risk for lymphoma. This risk is higher in patients with high disease activity and with more severe disease, including extra-articular involvement.”
Both doctors suggested that future research into the RA-cancer connection should focus on the disease mechanisms of RA that cause cancer to develop more frequently or more aggressively.
People who may be high-risk need to be identified, and the underlying biological mechanisms contributing to this correlation need to be investigated, they said.
Advice for patients
The Arthritis Foundation suggests that people with RA be mindful of whichever risk factors they’re able to control.
For example, quitting smoking is important, since RA and lung disease are linked at a higher prevalence and with a worse outlook and chance of death.
After all, it’s been found that people with RA who smoke are about 40 percent more likely to develop lung cancer than smokers who don’t have RA.
Researchers have noted that chronic inflammation may be a key component of an increased risk for cancer in people with RA.
The Arthritis Foundation’s website says that “an increased risk for a serious disease, even if it’s small, needs to be considered when deciding to take any medication.”
It later notes that uncontrolled RA can lead to serious and possibly dangerous health risks, too, so it’s important for people to weigh the risks and benefits when choosing a treatment plan to combat RA.