A recent groundbreaking study compared the cancer risks in rheumatoid arthritis patients and also the site-specific cancers. They found an increase in the all-cancer risk and also site-specific cancers like lung, bladder, cervix, and prostate cancers. The study results were published in the journal The Lancet: Regional Health.
Previous studies have highlighted an elevated cancer risk, ranging from 10% to 30%, in patients diagnosed with rheumatoid arthritis comApared to the general population. However, these studies often overlooked rarer forms of cancer. Recent therapeutic breakthroughs have the potential to influence this cancer risk, either by reducing disease activity or, conversely, by affecting the body's ability to combat cancer. The primary objective of this study is to assess the cancer risk in treated rheumatoid arthritis patients in comparison to the general population, both for all treated patients and based on the type of treatment received.

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This groundbreaking study is a nationwide, population-based analysis utilizing data from the French national claims database known as the "Système National des Données de Santé" (SNDS). The study spans from January 1, 2010, to December 31, 2020, and focuses on estimating the age and sex-standardized incidence ratios of cancer, both for all types and specific sites, in individuals with treated rheumatoid arthritis. The reference point for this estimation is the French population, based on data obtained from the French Network of Population-Based Cancer Registries (FRANCIM).
Findings:
Over the course of the study period, a total of 257,074 treated rheumatoid arthritis patients contributed to 2,098,238 person-years, forming the basis for the primary analysis.
The study uncovered that the overall cancer risk was higher in rheumatoid arthritis patients, with a Standardized Incidence Ratio (SIR) of 1.20 (95% CI [1.17–1.23]).
This elevated risk was particularly notable for specific types of cancer, including lung, bladder, cervix, and prostate cancers, as well as melanoma, diffuse large B-cell lymphoma, multiple myeloma, and Hodgkin's lymphoma.
Intriguingly, certain types of cancer were less frequent in rheumatoid arthritis patients than in the general population like pancreatic cancer, as well as breast and endometrial cancers.
The study also observed a modest yet statistically significant relative increase in the overall cancer risk over time among rheumatoid arthritis patients. However, there was a noticeable trend towards a decreased risk of non-Hodgkin's lymphoma.
Notably, the patients treated with rituximab, a medication used in the management of rheumatoid arthritis, displayed the highest risk of cancer among this cohort.
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Thus, through this study the researchers gave a comprehensive insight into the relationship between rheumatoid arthritis, its treatments, and cancer risk, shedding new light on this complex medical landscape.
Further reading: Risk of cancer for patients with rheumatoid arthritis versus general population: a national claims database cohort study. https://doi.org/10.1016/j.lanepe.2023.100768