Meta-Analysis Finds Link Between Ankylosing Spondylitis, Cancer Risk

Ankylosing spondylitis appeared to be associated with cancer development in a recent meta-analysis published in the journal Rheumatology.¹ However, more large-scale research is needed to analyze potential contributing factors such as the course of ankylosing spondylitis, medication exposures, and possible biases, according to the authors.

“While the etiology of ankylosing spondylitis remains elusive, inflammation is considered as a potential catalyst for its development,” the authors wrote. “Considering the connection between inflammation and cancer, there has been growing interest in studying the association between ankylosing spondylitis and cancer.”

In the pooled analysis, ankylosing spondylitis was associated with a greater risk of cancer occurrence. | Image credit: Lila Patel - stock.adobe.com

Although a meta-analysis published in 2016 found ankylosing spondylitis was linked with higher cancer risk,² that analysis did not categorize the cancers by organ type. In the time since, additional relevant data have been published. The authors of the new meta-analysis aimed to provide an update on the association between ankylosing spondylitis and cancer incidence.¹

The meta-analysis encompassed more than 330,000 participants in a total of 20 studies, with postoperative follow-up ranging from 0 to 27 years. Study locations included the US (n = 3), China (n = 4), Korea (n = 1), Western Australia (n = 1), and Sweden (n = 11). Nine of the studies explored risk for all types of cancers, and the remaining 11 examined the risks of specific cancers, including multiple myeloma, lymphoma, digestive system cancer, female cancer, plasma cell disorders, and hematologic malignancy, the authors noted.

In the pooled analysis, ankylosing spondylitis was associated with a greater risk of cancer occurrence, with a relative risk (RR) of 1.16 (95% CI, 1.07-1.26; P = .001; I² = 70.60%). Ankylosing spondylitis was associated with a higher cancer risk in Asia in the subgroup analysis, although the association did not reach statistical significance in Europe. An analysis that stratified studies by design found ankylosing spondylitis associated with a higher risk of cancer in retrospective studies, but not to a significant degree in prospective cohort studies.

Regarding specific cancer types, ankylosing spondylitis was linked with increased risks of the following malignancies:

• bone cancer (RR, 3.41; 95% CI, 1.45-7.99; P = .005; I² = 0.00%)
• thyroid gland cancer (RR, 1.76; 95% CI, 1.29-2.40; P < .001; I² = 13.70%)
• multiple myeloma (RR, 1.74; 95% CI, 1.42-2.15; P < .001; I² = 27.20%)
• leukemia (RR, 1.52; 95% CI, 1.27-1.82; P < .001; I² = 0.00%)
• kidney cancer (RR, 1.45; 95% CI, 1.08-1.94; P = .014; I² = 0.00%)
• prostate cancer (RR, 1.43; 95% CI, 1.17-1.74; P < .001; I² = 82.80%)
• non-Hodgkin lymphoma (RR, 1.42; 95% CI, 1.17-1.73; P < .001; I² = 0.00%)

There were no significant associations between ankylosing spondylitis and connective tissue cancer, brain cancer, testicular or other male cancers, bladder cancer, female cancers, skin cancers, digestive system cancers, or respiratory system cancers.

While there was significant heterogeneity, sensitivity analyses to identify the sources of heterogeneity found that none of the studies individually reversed the effects seen in the pooled analyses, the authors noted.

“These results indicate a potential link between ankylosing spondylitis and cancer, especially in bone, endocrine, head and neck, and hematological cancers,” the authors concluded. “Nevertheless, given current limitations in available data, there is a pressing need for future studies to meticulously account for influencing factors, including the course of the ankylosing spondylitis, medication histories, and potential biases introduced when using treatment as an exposure factor in investigating cancer risk.”

References

1. Yu L, Yan Y, Liu W, Huang S, Sun L, Ruan S. Association of ankylosing spondylitis with the risk of cancer: A meta-analysis of cohort studies. Rheumatology (Oxford). Published online June 3, 2024. doi:10.1093/rheumatology/keae294

2. Deng C, Li W, Fei Y, Li Y, Zhang F. Risk of malignancy in ankylosing spondylitis: A systematic review and meta-analysis. Sci Rep. 2016;6:32063. doi:10.1038/srep32063