We have herein presented a case of CD with rectal cancer at the residual rectum after multiple abdominal surgeries; the cancer was successfully treated with Ta-TME. Approximately 70 to 80% of patients with CD reportedly undergo surgical treatment [11, 12] and the rate of clinical anastomotic recurrence without drug therapy is around 20 to 25% per year . Although the long-term impact of improvements in pharmaceutical and biological therapy on surgical outcomes is still unknown, it is considered that many patients with CD might undergo several surgical treatments. It is clear that the more frequently patients undergo surgical treatment, the more difficult transabdominal operations become because of the development of intra-abdominal adhesions. The patient in this report underwent three abdominal operations before rectal cancer surgery. The difficulty of the operation for the residual rectal cancer was easily predicted, and severe adhesion was in fact observed during the laparoscopic surgery.
Cancer at the defunctioning residual rectum or rectal stump is also reportedly problematic in patients with Crohn’s coloproctitis after total colectomy [3, 4, 14], although colorectal cancer rarely occurs in the entire cohort of patients with CD. In patients with CD, end ileostomy with a closed rectal stump is sometimes selected for treatment of Crohn’s colitis because perianal complications or impaired healing of a perianal wound may occur [15, 16]. Although fecal diversion may reduce the rectal inflammation, rectal cancer at the residual rectum can develop. Lutgens et al.  reviewed the literature of rectal stump cancer, including 29 patients with CD. They showed that one of the risk factors for rectal stump cancer was the duration of the disease. von Roon et al.  reported that the risk of developing colorectal cancer in patients younger than 30 years of age at the time of diagnosis of CD was 9.50 to 21.46 times higher than that in the general population. Whereas the risk of CD-associated rectal cancer was reportedly comparable with the risk of rectal cancer in the general population [2, 17], a multicenter investigation in France revealed that the incident ratio of rectal cancer in patients with CD who developed a perianal inflammatory lesion was 0.77 cases per 1000 patient-years and that the risk of rectal cancer in patients with CD who developed a perianal lesion was 5.11 times higher than that in patients without a perianal lesion . These data indicate that a longer duration of extensive Crohn’s coloproctitis increases the risk of rectal cancer. We previously described a patient with CD who developed colitic cancer in the residual rectum following subtotal colectomy . He had developed CD at 20 years of age and underwent subtotal colectomy at 37 years of age; the residual rectal cancer developed 8 years after subtotal colectomy. The risk of residual rectal cancer was deemed to be high in our patient because he had been diagnosed with CD at 16 years of age and had a history of perianal inflammation. Although his cancer was not derived from the scar of the anal fistula, pathological findings showed inflammation of the remnant rectum; this inflammation may have caused his rectal cancer.
Since Ta-TME was at first reported by Lacy and Adelsdorfer in 2011 , this procedure has become widespread throughout the world. It is difficult to achieve TME for mid- or low-rectal cancer because the accessibility from the abdominal cavity to the distal rectum is reduced by the forward angle of the low rectum . In addition, obesity, a narrow pelvis, a bulky tumor, and pelvic irradiation make access to the low rectum and completion of TME more difficult [5, 6]. The transanal approach may provide clear visualization and detection of the correct dissection layer, facilitating complete TME . The potential benefits of Ta-TME are expected to include higher-quality TME with a better CRM, less morbidity, a lower frequency of conversion, and more sphincter-saving resection . Indeed, some of these benefits have been reported [6, 7, 21, 22]. Ta-TME is also considered to be useful in patients with a history of multiple abdominal surgeries. Narihiro et al.  reported a case of rectal cancer treated with Ta-TME in a patient who had undergone cholecystectomy, appendectomy, and Hartmann’s operation for sigmoid colon cancer. They concluded that they could overcome the difficulties of the transabdominal approach by Ta-TME; that is, the risks of bleeding and organ injury, longer duration of surgery, poor visual field due to intra-abdominal adhesion, poor surgical maneuverability, and loss of curability. In our case, although severe intra-abdominal adhesion was observed as predicted before the operation, Tp-TME facilitated detection of the correct plane of TME from the anal approach, reduced the duration of surgery by a two-team approach, avoided injury of organs adjacent to the rectum, and achieved negative pathological resection margin. The two-team approach also helped with the rectal dissection after rendezvous of the transabdominal and transperineal approaches. The appropriate dissection layer can sometimes be identified by applying tension to the tissue from both above and below. In addition, the advantages of Tp-TME also maximized in our case although the dissection between the rectum and the prostate was eventually performed laparoscopically. To dissect between the rectum and the prostate safely, the dorsal side of the prostate should be exposed from the lateral side. Although we finally dissected anterior side of the rectum laparoscopically, the transperineal approach played an important role to identify the correct layer between the rectum and the prostate.
Ta-TME is technically demanding and requires a proper anatomical perspective from the anal side. The data of the international registry of first Ta-TME cases revealed that misdirection of the correct layer occurred in 7.8% of cases and that injury to adjacent organs, including the urethra, occurred in 1.5% of cases . Recently, data from the national registry of Norway showed a high rate of local recurrence in patients who had undergone Ta-TME for rectal cancer . In this report, the 2-year local recurrence rate was > 10%, which was significantly higher than that associated with the laparoscopic approach. The authors speculated that gas pressure and surgical manipulation stressed the purse-string suture used to close the rectal lumen, resulting in spread of the cancer cells from the rectal lumen to the intra-abdominal cavity. In our department, a double purse-string suture is applied to tightly close the rectal rumen and prevent the spread of tumor cells. The international Ta-TME educational collaborative group provided recommendations for surgeons and centers as well as a training curriculum of Ta-TME . Surgeons should carefully introduce this procedure to their own institute, determine the indications for Ta-TME, and train their own clinicians according to the expert guidance.