Possible poor prognosis in younger‐onset Crohn's disease‐associated anorectal cancer: A subanalysis of the Nationwide Japanese study.

Background and aims: Crohn's disease (CD)‐associated intestinal cancers are characterized by their high incidence, particularly at the anorectal site in the Japanese population. Accumulating evidence revealed that younger‐onset sporadic colorectal cancer may exhibit unique biological features. To the best of our knowledge, few previous articles reported clinicopathological features in patients with CD‐associated anorectal cancer (CDAAC). Therefore, we aimed to clarify the relationship between the younger onset of cancer and clinicopathological characteristics and prognosis, and the efficacy of cancer surveillance in patients with CDAAC. Methods: CD patients who had been diagnosed with intestinal cancers from 1983 to 2020 were collected from 39 Japanese institutions in this study. Of 316 patients with CD‐associated intestinal cancers, we analyzed 211 patients with CDAAC. We divided the patients into two groups according to the median age at cancer diagnosis (45 years old). Results: Younger‐onset CDAAC (YO‐CDAAC) patients were significantly more likely to have a poor outcome than those with older‐onset CDAAC (OO‐CDAAC) in terms of both disease‐free survival (DFS) (p = 0.0014) and overall survival (OS) (p = 0.023). Multivariate analysis showed that age under 45 years old at diagnosis of cancer was one of the independent factors for poor DFS and OS (hazard ratios: 2.15, 95% confidence interval: 1.09–4.26, p = 0.028, hazard ratios: 1.95, 95% confidence interval: 1.05–3.60, p = 0.033, respectively). Patients detected via surveillance showed significantly better DFS and OS rates than symptomatic patients in YO‐CDAAC (p = 0.012 and 0.0031, respectively). Conclusions: YO‐CDAAC may have a poorer prognosis compared with OO‐CDAAC. Surveillance could be important to improve cancer prognosis, especially in young CD patients with anorectal disease. [ABSTRACT FROM AUTHOR]