Background/Purpose: Increasing evidence suggests that inflammation, a hallmark of rheumatoid arthritis (RA), is associated with an elevated risk of cancer and can influence cancer outcomes. Few studies have compared cancer outcomes among patients with cancer with or without RA and have conflicting results. We conducted this systematic literature review to evaluate the association between rheumatoid arthritis (RA) and cancer survival.

Methods: A comprehensive search was performed in PubMed, Embase, and Cochrane Central Register of Controlled Trials from inception through June 30, 2021. The search included observational studies, published in English, evaluating the association between RA and cancer mortality. Case series and reports were excluded. Data was extracted by three independent investigators (JH, AK, HK) using a predefined form, with conflicts resolved by a fourth reviewer (NS). Study quality assessments were conducted using Newcastle Ottawa Scale. Effect estimates for mortality (RA and cancer versus cancer only) were pooled using inverse variance weighting and random effects models using RevMan software.

Results: Eight retrospective cohort1–8 and two prospective cohort9,10 studies met our eligibility criteria. A total of 19,163 patients with both RA and any type of cancer were included, whereas 1,583,314 patients who had cancer only were included (Table 1). Three studies were from the USA, two from Sweden, and one study each from Finland, Canada, China, Taiwan, and Spain. Only two studies included estimates from multivariable analyses whereas crude mortality rates (CMR) were reported in 5 studies3,6,8–10. Due to heterogeneity between the studies, a meta-analysis was not conducted for RA and overall cancers. In a subgroup analysis, no association was observed between RA and survival after developing lung cancer with the pooled hazard ratio 1.04 [(95% CI: 0.98, 1.11)2,5–7 (Figure 1). The studies were rated as poor – good quality.

Conclusion: This study highlights the conflicting results on the association between RA and survival among patients with cancer due to variations in covariates controlled for and small sample sizes in few individual studies. The findings highlight the need for future large-scale studies that control for important confounders to better understand the interplay between RA and cancer survival outcomes.

References:
1. Abásolo L, et al. Semin Arthritis Rheum. 2008
2. Chen, Cy, et al. J Chin Med Assoc. 2005
3. Baecklund E, et al. Leuk Lymphoma. 2011
4. Hakulinen T, etal. Scand J Rheumatol. 1986
5. Nayak P, et al. AC&R 2017
6. Zhang L, et al. Thorac Cancer. 2020
7. Ji J et al. Rheumatology. 2011
8. Widdifield J, et al. Arthritis Care Res. 2018
9. Mikuls TR et al. Ann Rheum Dis. 2002
10.Mikuls TR, et al. J Clin Oncol. 2006

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/association-between-rheumatoid-arthritis-and-survival-after-cancer-a-systematic-literature-review-and-meta-analysis/