Department of Surgery, Coloproctology Center Takano Hospital, Kumamoto, Japan.
Department of Gastroenterological Surgery, Aichi Cancer Center Hospital, Aichi, Japan.
Cancer Med. 2022 Jul;11(14):2735-2743. doi: 10.1002/cam4.4631. Epub 2022 Mar 10.
Anal canal cancer (ACC) has been reported to be an uncommon cancer in Japan, as in the USA, Europe, and Australia. This retrospective multi-institutional study was conducted to clarify the characteristics of ACC in Japan. First, the histological ACC type cases treated between 1991 and 2015 were collected. A detailed analysis of the characteristics of anal canal squamous cell carcinoma (SCC) cases was then conducted. The results of the histological types revealed that of the 1781 ACC cases, 435 cases (24.4%) including seven cases of adenosquamous cell carcinomas were SCC and 1260 cases (70.7%) were adenocarcinoma. However, the most common histological type reported in the USA, Europe, and Australia is SCC. Most ACC cases are adenocarcinomas and there is a low incidence of SCC in Japan which is different from the above-mentioned countries. Moreover, we reclassified T4 into the following two groups based on tumor size: T4a (tumor diameter of 5 cm or less) and T4b (tumor diameter of more than 5 cm). The results of the TNM classification of SCC revealed that the hazard ratio (HR) to T1 of T2, T3, T4a, and T4b was 2.45, 2.28, 2.89, and 4.97, respectively. As T4b cases had a worse prognosis than T4a cases, we propose that T4 for anal canal SCC in Japan be subclassified into T4a and T4b.
肛管癌（ACC）在日本与美国、欧洲和澳大利亚一样，属于少见癌症。本回顾性多机构研究旨在阐明日本 ACC 的特征。首先，收集了 1991 年至 2015 年间治疗的组织学 ACC 型病例。然后对肛管鳞癌（SCC）病例的特征进行了详细分析。组织学类型的结果表明，在 1781 例 ACC 病例中，435 例（24.4%）包括 7 例腺鳞癌为 SCC，1260 例（70.7%）为腺癌。然而，在美国、欧洲和澳大利亚报告的最常见组织学类型是 SCC。大多数 ACC 病例为腺癌，日本 SCC 的发病率较低，与上述国家不同。此外，我们根据肿瘤大小将 T4 重新分为以下两组：T4a（肿瘤直径≤5cm）和 T4b（肿瘤直径>5cm）。SCC 的 TNM 分类结果表明，T2、T3、T4a 和 T4b 相对于 T1 的危险比（HR）分别为 2.45、2.28、2.89 和 4.97。由于 T4b 病例的预后较 T4a 病例差，因此我们建议将日本肛管 SCC 的 T4 进一步分为 T4a 和 T4b。
