Background Anal canal carcinoma (ACC) is reported to be a rare cancer worldwide. In Japan, while the incidence rate is similarly low compared to Western countries, its histological distribution differs. This paper aimed to clarify the epidemiological characteristics of ACC, particularly anal canal squamous cell carcinoma (SCC), in Japan and to compare them with Western data. Methods The epidemiological data were taken from the Japanese Society for Cancer of the Colon and Rectum (JSCCR) registry and a nationwide multi-institutional study. Clinicopathological features, human papillomavirus (HPV) status, treatment trends, and survival were analyzed. The comparative data were derived from major Western registry studies. Results In Japan, adenocarcinoma accounted for 66.8–75.5% of the ACC cases, while SCC represented only 16.2–24.4%, in contrast to the 70–85% SCC predominance reported in Western countries. Among Japanese SCC cases, women accounted for 71.5%, a higher proportion than in Western countries. HPV was positive in 85% of the SCC cases, with HPV-16 as the most prevalent genotype, which is consistent with global patterns. The adoption of chemoradiotherapy (CRT) increased from 14% in the 1990 s to over 80% after 2010, achieving survival outcomes comparable to surgery. Conclusions In Japan, adenocarcinoma was the predominant type of ACC, while SCC was less common. However, the characteristics of HPV-associated SCC were similar to those observed in Western countries. Standardization of classification and staging criteria and the expansion of HPV vaccination may be essential to improve clinical management and facilitate international comparisons.
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In 2024, the second edition of the Japan Society of Coloproctology (JSCP) Practice Guidelines for Fecal Incontinence was published in Japan, followed by the release of this English version. This marks the first major revision in 7 years since the publication of the first edition. The second edition was completed over a span of 3 years, and its overview and key features are summarized below. This guideline begins with a clinical flowchart outlining the general diagnostic and therapeutic approach. A notable update is the inclusion of insertable anal and vaginal continence devices, which are now considered a form of conservative therapy under clinical research frameworks. In Chapter I-B (Epidemiology), the prevalence of anal incontinence was newly reported: among a Japanese population with an average age of 35 years, 15.5% of men and 42.7% of women were affected. In Chapter II (Diagnosis), the utility of a bowel diary for patient assessment is discussed for the first time. The guideline also provides a detailed description of the evaluation method for digital rectal examination. Additionally, a new section was added addressing incontinence-associated dermatitis (IAD), including its risks and methods of assessment. In Chapter III (Diagnostic Testing), the guideline expands upon previously established diagnostic tests by newly including detailed descriptions of ultrasound techniques-specifically, endoanal ultrasound, transperineal ultrasound, and transvaginal ultrasound. Chapter IV (Treatment) outlines conservative treatment strategies, including dietary guidance, bowel habit instruction, and care for fecal incontinence. Pharmacologic therapies are presented with itemized explanations by drug type. Pelvic floor muscle training, biofeedback therapy, and transanal irrigation are classified under "specialized conservative therapies" and discussed in detail. For surgical treatment, a new Clinical Question (CQ) addresses postpartum fecal incontinence. It recommends early referral to a specialized center when a sphincter injury is present to be repaired, whereas observation for one year may be appropriate when no injury is identified. Another new CQ discusses the mode of delivery in subsequent pregnancies following obstetric anal sphincter injuries (OASIS), emphasizing the need to evaluate fecal incontinence severity, anal sphincter function, and its integrity before making clinical decisions. Stoma creation is described in detail as one of the surgical treatment options, including its implications for improved postoperative quality of life. For the first time, regenerative therapy for the anal sphincter is introduced as a novel surgical option, reporting promising long-term outcomes from trials involving the transplantation of autologous cultured myoblasts into the external anal sphincter. Finally, Chapter V addresses special clinical scenarios in detail, including fecal incontinence associated with neurological and spinal disorders, dementia, frailty, and bedridden elderly patients.
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