In recent years, robotic-assisted surgery has demonstrated remarkable progress as a minimally invasive procedure for colorectal cancer. While there have been fewer studies investigating robotic-assisted surgery for the treatment of colon cancer than rectal cancer, evidence regarding robotic-assisted colectomy has been accumulating due to increasing use of the procedure. Robotic-assisted colectomy generally requires a long operative time and involves high costs. However, as evidence is increasingly supportive of its higher accuracy and less invasive nature compared to laparoscopic colectomy, the procedure is anticipated to improve the ratio of conversion to laparotomy and accelerate postoperative recovery. Robotic-assisted surgery has also been suggested for a specific level of effectiveness in manipulative procedures, such as intracorporeal anastomosis, and is increasingly indicated as a less problematic procedure compared to conventional laparoscopy and open surgery in terms of long-term oncological outcomes. Although robotic-assisted colectomy has been widely adopted abroad, only a limited number of institutions have been using this procedure in Japan. Further accumulation of experience and studies investigating surgical outcomes using this approach are required in Japan.

Pelvic organ prolapse (POP) is a condition wherein one or more of the organs in the pelvis slip down from their original position and protrude into the vagina. Pelvic organ prolapse surgery has increased in the urogynecological field due to higher aging society. POP patients often suffer from bowel dysfunction, such as difficulty of bowel movements and the need to strain or push on the vagina to have a bowel movement. Rectocele is often treated with the same method used for POP, but sometimes it is treated transanally. In the transabdominal approach, the vagina is divided from the rectum, and the mesh is fixed between the vagina and rectum.

On the other hand, rectal prolapse is a condition wherein the rectum slips down from its original position and protrudes from the anus. Like POP surgery, rectal prolapse has been treated laparoscopically. Even though the protruding position is different, both are pelvic conditions, and the concept of treatment is similar. Recently, POP and rectal prolapse have been diagnosed at the same time, and sometimes these diseases have been treated together.

In the higher aging society, incidences of POP and rectal prolapse will increase, and both will have greater chance to be treated. Although POP is a urogynecological disease, coloproctologists need to know the bowel dysfunction in order to treat POP.

Anal squamous cell carcinoma (SCC) is rare, but it has been commonly detected as an invasive cancer. The standard treatment for anal SCC was surgical resection. However, recent medical advances have enabled the standard treatment to be chemoradiotherapy. Anal intraepithelial neoplasia (AIN) is a premalignant lesion of SCC. The screening test for AIN and human papilloma virus vaccine are important for the following high-risk patients: patients positive for human immunodeficiency virus and men who have sexual intercourse with men. Although cytology can be easily applied for a screening test, the false-negative rate for AIN is high. Instead, high-resolution anoscopy (HRA) has been gaining attention as a promising screening method for high-risk patients. Investigations comparing characteristic findings of HRA with the histology of AIN have demonstrated that HRA is a highly specific test for AIN.

Magnifying or image-enhanced endoscopies are also routinely used for colonoscopy, as they allow detailed observations at higher magnifications than those of HRA. Hence, these endoscopic modalities can be applied for assessing AIN. Ablation therapies or topical medications are available as the local treatment for AIN. Although endoscopic submucosal dissection is considered to be feasible to remove AIN, it has a technical difficulty to approach endoscopically invisible areas. Hence, this technique may be useful to resect AIN localized in the endoscopically visible areas, when the localization is confirmed via targeted biopsy.

In the 1950s, the cause of anal fistulas was identified as an infection of the anal gland (cryptoglandular infection theory). Thereafter, treatment for this disorder began in the 1960s with the lay-open procedure, which involved incising the sphincter and the fistula tract. However, it was found that too much invasion into the sphincter could result in postoperative fecal incontinence. Thus, to reduce such risk, sphincter-preserving surgery was applied for superficial anal fistula in 1961 and for deep anal fistula (ischiorectal fistula) in 1965. Over the years, more effective sphincter-preserving procedures for ischiorectal fistula have been developed to improve the quality of life of the patient. In this review article, we aim to first introduce the basic surgical techniques for ischiorectal fistula. We will discuss the anatomy of the anus and the pathogenesis of ischiorectal fistula and will provide some diagnostic methods. Representative sphincter-preserving procedures that have been performed for ischiorectal fistula since 1965 will also be categorized and outlined chronologically. The discussion will look at the following techniques for ischiorectal fistula and outline the advantages and disadvantages of each procedure so that they can be used as a reference for ischiorectal fistula surgery in the future: the lay-open procedure (fistulotomy and fistulectomy), the Hanley procedure (first partial sphincter-preserving procedure), the muscle-filling procedure, the Moriya method and Ui method (modified partial sphincter-preserving procedure), the Takano method and the sphincter-preserving lateral procedure (complete sphincter-preserving procedure), the seton method (a cross between the lay-open procedure and sphincter-preserving procedure), and the overseas sphincter-preserving procedure.

Objectives: The role of enterocele in the obstructed defecation syndrome (ODS) has remained to be controversial, as patients with enterocele frequently exhibit multiple risk factors, including aging, parity, concomitant different abnormalities, previous histories of pelvic surgery, and incomplete emptying of the rectum. Thus, in this study, we aimed to investigate the association between enterocele and ODS using multivariate analysis.

Methods: Between June 2013 and June 2021, 336 women underwent defecography as they had symptoms of ODS. Of those, 293 women (87%) who had anatomical abnormalities were included in this study.

Results: Enterocele was detected in 104 (36%) patients. More women with enterocele had histories of hysterectomy compared to those without enterocele (29% vs. 10%, P < 0.0001). The frequency of radiological incomplete emptying was found to be significantly lower in women with enterocele (36%) than in those without enterocele (50%), whereas the mean (95% confidence interval) ODS scores in women with enterocele were significantly higher than those without enterocele [12.1 (11.0-13.3) versus 10.8 (10.5-11.5), P = 0.023]. As per the results of our multivariate analysis, it was determined that the presence of enterocele was associated with higher ODS scores (P = 0.028). However, the small differences in the mean score (1.3) would be clinically negligible. The specific radiological type of enterocele which compressed the rectal ampulla at the beginning of defecation was not associated with the increased ODS scores.

Conclusions: The presence of enterocele may not be a primary cause of ODS. Other anatomical abnormalities combined with enterocele, or the hernia itself, may have a role in causing ODS.

Objectives: This retrospective study was conducted to clarify the morphological characteristics of colorectal cancer (CRC) in Japanese familial adenomatous polyposis (FAP) patients.

Methods: This study was carried out by the study group for FAP of the Japanese Society for Cancer of the Colon and Rectum. FAP patients who underwent surgical resection between 2000 and 2012 were included in the study.

Results: Of the 303 patients enrolled, 119 patients without CRC were excluded. Of 523 lesions, 49 lesions with missing morphological information were excluded; hence, only 474 CRC lesions in 178 patients (328 superficial lesions in 122 patients and 146 non-superficial lesions in 92 patients) were included in the study. Depressed lesions accounted for 3.0% of superficial lesions and ulcerated lesions accounted for 84.9% of non-superficial lesions. The depressed superficial lesions were observed only in patients with sparse and attenuated FAP (P = 0.003). The age of the patients at surgery differed between the two groups, with patients with depressed superficial lesions being significantly older than those with non-depressed superficial lesions (P = 0.009). Moreover, the age of the patients at FAP diagnosis differed between the two groups, with patients with ulcerated non-superficial lesions being significantly older than those with protruded non-superficial lesions (P = 0.006).

Conclusions: In patients with FAP, depressed superficial CRC lesions rarely developed but were detected in our study group, and ulcerated non-superficial CRC lesions were also present with similar ratios. Clinicians should pay attention to depressed superficial lesions during endoscopic surveillance of FAP patients.

Objectives: The ideal cut-off value for the diameter of metastasis-positive lymph nodes (LNs) in patients with colorectal neuroendocrine neoplasms (NENs) is unclear. Thus, in this study, we investigated the correlation between the LN diameter and LN metastasis.

Methods: A total of 148 LNs of 42 patients with colorectal NEN who underwent surgical dissection or local resection from April 2010 to March 2016 were included in the present study. The LN diameters were measured on computed tomography, and LN metastases were either pathologically proven or evaluated during the follow-up period.

Results: Overall, 18 (12.2%) LNs were positive for LN metastasis, and 130 (87.8%) were negative. The short diameter in metastatic-positive LNs was longer than that in negative LNs (4.9 [3.0-6.3] vs. 2.0 [1.0-2.0] mm; P = 0.01). An LN of >3 mm predicted LN metastasis with 88.8% sensitivity and 78.5% specificity with an area under the curve of 0.852.

Conclusions: Surgical resection with lymphadenectomy should be considered for patients with LNs of >3 mm in diameter.

Objectives: In elderly colorectal cancer (CRC) patients, preoperative surgical indications can be controversial in some cases depending on the patient's physical condition. In comparison with younger patients, both cancer-specific survival (CSS) and non-CCS (NCSS) have an impact on the prognosis and both CSS and NCSS should be considered in the preoperative assessment. We aimed to investigate the impact of body mass index (BMI) on CSS and NCSS in Japanese elderly CRC patients.

Methods: We retrospectively collected data from 471 Japanese elderly patients (≥80 years) with stage I-III CRC who underwent curative surgery from 1998 to 2017. A Kaplan-Meier survival analysis with propensity score matching (PSM) and a multivariate Cox regression analysis were performed.

Results: After PSM, 123 higher BMI (≥23) and 123 lower BMI (<23) cases were matched. The higher BMI group had significantly better survival than the lower BMI group regarding NCSS and overall survival (OS; P <.001 and P <.001, respectively). The multivariate survival analysis further confirmed that the higher BMI group had significantly better survival than the lower BMI group regarding CSS, NCSS, and OS (P =.027, P <.001, and P <.001, respectively).

Conclusions: In Japanese elderly patients with stage I-III CRC who underwent curative surgery, preoperative higher BMI was a significant and simple favorable prognostic predictor, especially for NCSS and OS.