Patients with rheumatoid arthritis and autoimmunity face an elevated risk for cancer, but now researchers have found that the reverse may also be true.

Many people with rheumatoid arthritis (RA) have been told they are at a higher risk for cancer because of the disease and the treatments, such as biologics and immunosuppressants, they undergo.

But what these patients, and perhaps even their doctors, didn’t know until recently is that cancer medications may cause RA, too.

There’s been a long-known link between cancer and RA. Typically, the risk has been presented that RA patients face an elevated risk for cancer, but not the other way around.

A recent study published in the Annals of Rheumatic Disease recommends that oncologists should now monitor cancer patients who are undergoing immunotherapy treatments because those therapies may put patients at higher risk for developing RA.

Read more: Stem cell treatment a possible therapy for rheumatoid arthritis »

Many RA patients and others with chronic autoimmune diseases have a hematologist or oncologist in their doctor “tool kit.”

But, a rheumatologist isn’t necessarily a doctor that a cancer patient would be working with.

Oncologists must be aware of this new potential for rheumatic diseases among cancer patients who have been treated with a class of drugs called immune checkpoint inhibitors (ICIs), according to the authors of the study.

The team of 13 researchers followed 13 patients who received ICIs and developed immune-related adverse events (IRAEs).

The average age of the study participants was 58, and their types of cancer included skin cancer, lung cancer, and renal cell carcinoma.

Nine of these patients developed inflammatory arthritis that was diagnosed via imaging or in testing synovial joint fluid.

Four of the patients developed Sjogren’s syndrome, which is also a rheumatic disease.

All of the cancer patients who developed rheumatic and other autoimmune conditions were only on ICIs for a short time, and developed their IRAE in nine months or less after treatment.

Read more: Rheumatoid arthritis linked to serious mood disorders »

Researchers said the short turnaround highlights how quickly the immune and rheumatologic manifestations took place.

Patients who developed symptoms were put on corticosteroids, a common treatment for RA. Some were also given methotrexate or a biologic such as an anti-tumor necrosis factor (anti-TNF) drug, which are also common therapies for RA.

In the full version of the published report, the authors of the study concluded that, “Recognizing the potential for ICIs to cause IRAEs that resemble more classical autoimmune diseases will become increasingly important to rheumatologists as more patients are referred for evaluation and management, and to oncologists who must recognize these toxicities in order to refer.”

The team also noted the “need for careful baseline evaluation and following [up] of these patients by rheumatologists.” The researchers also stated in a press release regarding the published study, that a coordinated and cooperative effort between rheumatologists is not only crucial, but may become the new normal, saying that such a relationship “will be instrumental to understand the spectrum of rheumatological IRAEs and their treatment.”

Oncologists will have to be vigilant in investigating patient-reported symptoms and blood test results in order to decide when to refer a cancer patient to a rheumatologist.

Read more: The latest cancer linked to RA is cervical cancer »