Arthritis does not transform into cancer; these are distinct diseases with different underlying biological processes. However, certain types of arthritis, particularly inflammatory forms, can be associated with an increased risk for specific cancers. This connection does not imply that one disease directly becomes the other, but rather that shared risk factors, disease mechanisms, or treatments can influence the likelihood of cancer development in individuals with arthritis.
Understanding the Connection: Chronic Inflammation
Chronic inflammation serves as a primary mechanism linking certain types of arthritis to an elevated cancer risk. While inflammation is a normal immune response, its persistent presence can contribute to cellular changes that promote cancer development. Sustained inflammation can damage DNA, leading to mutations characteristic of cancerous cells.
Chronic inflammation can suppress the immune system’s ability to identify and eliminate abnormal cells, creating an environment conducive to tumor growth. It fosters a microenvironment that supports the proliferation of pre-malignant cells. Inflammatory cells often release cytokines and other molecules that can drive tumor initiation, progression, and even metastasis.
Specific Arthritis Conditions and Cancer Risk
Rheumatoid Arthritis (RA), a chronic autoimmune condition, shows a notable association with increased cancer risk. Individuals with RA have approximately double the average risk for developing lymphoma, a type of blood cancer. This heightened risk is thought to stem from chronic immune system stimulation where the same lymphocytes that become cancerous in lymphomas are highly active in RA. RA is also linked to an increased risk of lung cancer, and some skin cancers like basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Other identified associations include higher risks for cervical cancer, oropharyngeal cancer, bladder cancer, prostate cancer, melanoma, diffuse large B cell lymphoma, and Hodgkin’s lymphoma. Some studies suggest a potentially lower risk for breast, endometrial, and colorectal cancers in RA patients.
Psoriatic Arthritis (PsA), an inflammatory condition often occurring with psoriasis, has mixed findings regarding its overall cancer risk. Research indicates an increased incidence of certain cancers, particularly breast cancer and non-melanoma skin cancer. The association with skin cancer may be linked to the presence of psoriasis itself and certain treatment methods. PsA has also been tied to a potential increase in lung cancer, bladder cancer, and lymphoma.
Ankylosing Spondylitis (AS) also carries an elevated overall cancer risk. Specific cancers associated with AS include bone cancer, colon cancer, prostate cancer, and hematological malignancies such as lymphoma and multiple myeloma. There is also an increased risk for upper gastrointestinal cancer, thyroid gland cancer, and kidney cancer in individuals with AS. The chronic inflammation characteristic of AS contributes to DNA damage, which can lead to cancer development.
Medications and Other Influencing Factors
Certain medications for arthritis, particularly those that suppress the immune system, can influence cancer risk. Immunosuppressants such as methotrexate have been associated with a slightly increased risk of lymphoma, especially in patients with Epstein-Barr virus. Methotrexate has also been linked to an increased risk of skin cancer.
Biologic and targeted synthetic DMARDs, while effective in controlling inflammation, also warrant consideration. Some biologics and JAK inhibitors have been linked to an increased cancer risk. However, a significant body of evidence suggests that uncontrolled inflammation from the underlying arthritic condition poses a greater cancer risk than the medications, and the benefits of these treatments in controlling disease often outweigh the potential risks.
Beyond disease and medications, lifestyle factors also play a role in cancer risk for individuals with arthritis. Smoking increases the risk for both arthritis and various cancers, including lung cancer. Obesity and alcohol consumption are additional factors that contribute to overall cancer risk and can exacerbate arthritic conditions. Maintaining a balanced diet, regular physical activity, and adhering to recommended cancer screenings are important strategies for managing overall health and reducing cancer risk.