Revolutionizing sphincter preservation in ultra-low rectal cancer: exploring the potential of transanal endoscopic intersphincteric resection (taE-ISR): a propensity score-matched cohort study

BACKGROUND

With the optimization of neoadjuvant treatment regimens, the indications for intersphincteric resection (ISR) have expanded. However, limitations such as unclear surgical field, impaired anal function, and failure of anal preservation still exist. Transanal total mesorectal excision can complement the drawbacks of ISR. Therefore, this study combined these two techniques and proposed transanal endoscopic intersphincteric resection (taE-ISR), aiming to explore the value of this novel technique in anal preservation for ultra-low rectal cancer.

MATERIAL AND METHODS

Four high-volume centres were involved. After 1:1 propensity score-matching, patients with ultra-low rectal cancer underwent taE-ISR ( n =90) or ISR ( n =90) were included. Baseline characteristics, perioperative outcomes, pathological results, and follow-up were compared between the two groups. A nomogram model was established to assess the potential risks of anal preservation.

RESULTS

The incidence of adjacent organ injury (0.0% vs. 5.6%, P =0.059), positive distal resection margin (1.1% vs. 8.9%, P =0.034), and incomplete specimen (2.2% vs. 13.3%, P =0.012) were lower in taE-ISR group. Moreover, the anal preservation rate was significantly higher in taE-ISR group (97.8% vs. 82.2%, P =0.001). Patients in the taE-ISR group showed a better disease-free survival ( P =0.044) and lower cumulative recurrence ( P =0.022) compared to the ISR group. Surgery procedure, tumour distance, and adjacent organ injury were factors influencing anal preservation in patients with ultra-low rectal cancer.

CONCLUSION

taE-ISR technique was safe, feasible, and improved surgical quality, anal preservation rate and survival outcomes in ultra-low rectal cancer patients. It held significant clinical value and showed promising application prospects for anal preservation.

Optimizing the selection of patients with low rectal cancer for intersphincteric resection by evaluating vertical invasion to the levator and external sphincter

AIM

The indications for intersphincteric (ISR) anterior resection are not clearly defined. The aim of this study was to evaluate vertical extension of T2 or T3 low rectal cancer treated by rectal amputation to optimize patient selection for ISR.

METHOD

The abdominoperineal excision specimens of T2 or T3 low rectal cancer from 53 patients treated between 1992 and 2004 were retrospectively reviewed. Vertical invasion was quantified by measuring the shortest distance between the tumour and the striated muscle (T-SM), assuming that this represented the surgical margin that would have be achieved had an ISR been performed.

RESULTS

Involvement of the dentate line (DL) and intramural distal spread were independent risk factors for T-SM ≤ 2 mm. The T-SM was less when the inferior border of the tumour was on the distal side of the DL (r = 0.572, P < 0.001). The probability of involvement of the DL, intramural distal spread or either one of these being associated with T-SM ≤ 2 mm was 43, 46 and 43%, respectively. All patients without both intramural distal spread and involvement of the DL had T-SM > 2.

CONCLUSION

We recommend that ISR should only be performed for patients with T2 or T3 low rectal cancer in whom the lowest edge of the tumour is above the DL and there is no intramural distal spread. Such patients are relatively unlikely to have a T-SM ≤ 2 mm.