Initial experience with transanal endoscopic microsurgery: the need for understanding the limitations

Risk of recurrence after local resection of T1 rectal cancer: a meta-analysis with meta-regression

BACKGROUND

T1 rectal cancer (RC) patients are increasingly being treated by local resection alone but uniform surveillance strategies thereafter are lacking. To determine whether different local resection techniques influence the risk of recurrence and cancer-related mortality, a meta-analysis was performed.

METHODS

A systematic search was conducted for T1RC patients treated with local surgical resection. The primary outcome was the risk of RC recurrence and RC-related mortality. Pooled estimates were calculated using mixed-effect logistic regression. We also systematically searched and evaluated endoscopically treated T1RC patients in a similar manner.

RESULTS

In 2585 unique T1RC patients (86 studies) undergoing local surgical resection, the overall pooled cumulative incidence of recurrence was 9.1% (302 events, 95% CI 7.3-11.4%; I2 = 68.3%). In meta-regression, the recurrence risk was associated with histological risk status (p < 0.005; low-risk 6.6%, 95% CI 4.4-9.7% vs. high-risk 28.2%, 95% CI 19-39.7%) and local surgical resection technique (p < 0.005; TEM/TAMIS 7.7%, 95% CI 5.3-11.0% vs. other local surgical excisions 10.8%, 95% CI 6.7-16.8%). In 641 unique T1RC patients treated with flexible endoscopic excision (16 studies), the risk of recurrence (7.7%, 95% CI 5.2-11.2%), cancer-related mortality (2.3%, 95% CI 1.1-4.9), and cancer-related mortality among patients with recurrence (30.0%, 95% CI 14.7-49.4%) were comparable to outcomes after TEM/TAMIS (risk of recurrence 7.7%, 95% CI 5.3-11.0%, cancer-related mortality 2.8%, 95% CI 1.2-6.2% and among patients with recurrence 35.6%, 95% CI 21.9-51.2%).

CONCLUSIONS

Patients with T1 rectal cancer may have a significantly lower recurrence risk after TEM/TAMIS compared to other local surgical resection techniques. After TEM/TAMIS and endoscopic resection the recurrence risk, cancer-related mortality and cancer-related mortality among patients with recurrence were comparable. Recurrence was mainly dependent on histological risk status.

Can transanal endoscopic microsurgery effectively treat T1 or T2 rectal cancer?A systematic review and meta-analysis

AIM

We aimed to compare the safety and oncological outcomes of transanal endoscopic microsurgery (TEM) and radical surgery (RS) for patients with T1 or T2 rectal cancer.

METHOD

We searched Pubmed, Embase, Cochrane Library databases for relevant studies comparing TEM with RS in rectal cancer published until April 2020. We focused on safety and oncological outcomes.

RESULTS

This meta-analysis included 3526 patients from 12 studies. Compared with RS, TEM had a shorter operative time (weighted mean difference [WMD] -110.02, 95% confidence interval [CI]: 143.98, -76.06), less intraoperative blood loss (WMD -493.63, 95% CI: 772.66, -214.59), lower perioperative morality (risk ratio [RR] 0.25, 95% CI: 0.06, 0.99), and fewer postoperative surgical complications (RR 0.23, 95% CI: 0.11,0.45). TEM was associated with more patients with a positive margin or a doubtfully complete margin than RS (RR 7.36, 95% CI: 3.66, 14.78). TEM was associated with higher local recurrence (RR 2.63, 95% CI: 1.60, 4.31) and overall recurrence (RR 1.60, 95% CI: 1.09, 2.36). TEM had a negative effect on 5-year overall survival (hazard ratio [HR] 1.51, 95% CI: 1.16, 1.96), especially in the T2 without neoadjuvant therapy (NAT) subgroup (HR 2.02, 95% CI: 1.32, 3.09), but in the subgroups of T1 or T2 with NAT before TEM, TEM did not yield a significantly lower overall survival than RS.

CONCLUSION

TEM seems appropriate for T1 rectal cancer with favourable histopathology. For patients with T2 rectal cancer, NAT before TEM may contribute to achieving oncological outcomes equivalent to that achieved with RS.

Transanal Minimally Invasive Surgery

Transanal endoscopic surgery (TES) techniques encompass a variety of approaches, including transanal endoscopic microsurgery and transanal minimally invasive surgery. These allow a surgeon to perform local excision of rectal lesions with minimal morbidity and the potential to spare the need for proctectomy. As understanding of the long-term outcomes from these procedures has evolved, so have the indications for TES. In this study, we review the development of TES, its early results, and the evolution of new surgical techniques. In addition, we evaluate the most recent research on indications and outcomes in rectal cancer.

Minimal access surgery for rectal cancer: an update

Minimally invasive or minimal access surgery (MAS) for colon and rectal cancer was introduced in the early 1990s. Although laparoscopic colon surgery is now practiced worldwide, technical barriers, including a steep learning curve, preclude the widespread adoption of MAS techniques for rectal cancer. In addition, although randomized controlled trials have demonstrated that MAS techniques for colon cancer are oncologically equivalent to open surgery, similar confirmatory studies for rectal cancer have yet to be reported. In this Review, current evidence in support of laparoscopic and robotic total mesorectal excision for rectal cancer resection is presented. Other MAS approaches, such as transanal endoscopic microsurgery and natural orifice transluminal endoscopic surgery, are also discussed.

Evaluation of colonoscopy in the diagnosis and treatment of rectal carcinoid tumors with diameter less than 1 cm in 21 patients

The aim of this study was to evaluate colonoscopy in the diagnosis and treatment of rectal carcinoid tumors with diameter <1 cm. Elevated lesions with normal mucosal appearance under colonoscopy were identified. Endoscopic ultrasound (EUS) was performed in 16 patients. Lesions diagnosed as rectal carcinoid tumors were resected by endoscopic mucosal resection (EMR). The diagnosis of specimens by EMR was confirmed by pathological examination. Immunohistochemical staining was undertaken and follow-up data were collected. Twenty-two lesions were found among the 21 cases. The majority of these were located within 10 cm of the anal opening. Twenty two cases with rectal carcinoids were diagnosed by EUS under colonoscopy and all cases were verified by pathological examination. The resection rate was 95.5% (21/22). Of the lesions, six were mucosal and 10 were submucosal. Immunohistochemistry was undertaken for carcinoid tumors. Histological patterns of rectal carcinoids revealed solid nests or trabecular patterns. Eleven cases were synaptophysin (SYN)-positive, 8 cases were neurone-specific enolase (NSE)-positive and 5 cases were chromogranin A (CgA)-positive. Colonoscopy combined with EUS is effective in the diagnosis and determination of small rectal carcinoids. Endoscopic treatment is effective for small-sized tumors. Pathology and immunohistochemistry remain the diagnostic gold standard.