Distal margin distance in radical resection of locally advanced rectal cancer after neoadjuvant therapy

Colorectal cancer has a high incidence and mortality rate in China, with the majority of cases being middle and low rectal cancer. Surgical intervention is currently the main treatment modality for locally advanced rectal cancer, with the common goal of improving oncological outcomes while preserving function. The controversy regarding the circumferential resection margin distance in rectal cancer surgery has been resolved. With the promotion of neoadjuvant therapy concepts and advancements in technology, treatment strategies have become more diverse.Following tumor downstaging, there is an increasing trend towards extending the safe distance of distal rectal margin. This provides more opportunities for patients with low rectal cancer to preserve their anal function.However, there is currently no consensus on the specific distance of distal resection margin.

Real-time in vivo distal margin selection using confocal laser endomicroscopy in transanal total mesorectal excision for rectal cancer

BACKGROUND Transanal total mesorectal excision(TaTME)allows patients with ultralow rectal cancer to be treated with sphincter-saving surgery.However,accurate delineation of the distal resection margin(DRM),which is essential to achieve R0 resection for low rectal cancer in TaTME,is technically demanding.AIM To assess the feasibility of optical biopsy using probe-based confocal laser endomicroscopy(pCLE)to select the DRM during TaTME for low rectal cancer.METHODS A total of 43 consecutive patients who were diagnosed with low rectal cancer and scheduled for TaTME were prospectively enrolled from January 2019 to January 2021.pCLE was used to determine the distal edge of the tumor as well as the DRM during surgery.The final pathological report was used as the gold standard.The diagnostic accuracy of pCLE examination was calculated.RESULTS A total of 86 pCLE videos of 43 patients were included in the analyses.The sensitivity,specificity and accuracy of real-time pCLE examination were 90.00%[95%confidence interval(CI):76.34%-97.21%],86.96%(95%CI:73.74%-95.06%)and 88.37%(95%CI:79.65%-94.28%),respectively.The accuracy of blinded pCLE reinterpretation was 86.05%(95%CI:76.89%-92.58%).Furthermore,our results show satisfactory interobserver agreement(κ=0.767,standard error=0.069)for the detection of cancer tissue by pCLE.There were no positive DRMs(≤1 mm)in this study.The median DRM was 7 mm[interquartile range(IQR)=5-10 mm].The median Wexner score was 5(IQR=3-6)at 6 mo after stoma closure.CONCLUSION Real-time in vivo pCLE examination is feasible and safe for selecting the DRM during TaTME for low rectal cancer(clinical trial registration number:NCT04016948).