Colorectal cancer is one of the leading deadly diseases in the world. Due to the TME (total mesorectal excision) for the last decades, the survival and relapse rate of rectal cancer patients have been considerably improved. However, anatomical limitations in pelvic space hinder the further optimization of surgical treatment Thus, the natural orifice transluminal endoscopic surgery (NOTES) emerges as an alternative surgical strategy. Of note, transanal total mesorectal excision (TaTME) , a new invention based on TME principle, NOTES conception and single port technique, has been prevailing both in West and East nations, with or without the abdominal laparoscopic assistance. Up to date, there are various kinds of instruments and patterns to complete TaTME with comparable clinical outcomes. However, flaws in each instrument remains according to the feedbacks. This study is therefore designed to clinically evaluate the feasibility and safety of the new instruments specifically for TaTME (CS-Compact, GelPoint pathway).

Rectal cancer comprises the most in colorectal cancer around the world, among which surgery remains the optimal therapeutic intervention. The TME (Total Mesorectal Excision), proposed by Bill Heald, provides novel insights for the eradication of possible disseminated cancer cells and therefore reduces the recurrence and mortality rates. However, either laparoscopic or open TME surgery is limited by the pelvic space and further improvement. For the last decade, the emerging of the natural orifice transluminal endoscopic surgery (NOTES) offers an alternative pattern for rectal cancer surgery, among which, the TaTME (transanal total mesorectal excision) represents the most optimized surgery techniques. Derived from TME, NOTES and modified laparoscopic instruments, TaTME facilitates the dissection process of rectal cancer from caudal to cranial, from indirect to direct vision. TaTME allows for accurate confirmation of resected margin with proper transecting level, better dissection of mesorectum and protection of sphincter, a qualified end-to-end anastomosis and reduced need of endolinear stapler and possible leakage afterwards. However, various kinds of instruments and surgical procedures have been proposed to complete TaTME, all of which have been validated by preclinical and clinical trials in small size. Of note, this study is initiated to apply a suit of instruments specifically designed for TaTME ( GelPoint pathway CS-Compact) and clinically evaluate the feasibility and safety of the new instruments without comparison to other prevailing ones. The CS-Compact and GelPoint pathway has been confirmed both safe and feasible to operate in preclinical trials and clinical trials in western. This study strictly examines the corresponding issues in Chinese rectal cancer patients. The surgeons in our institute have successfully completed the training programs of TaTME in preclinical trials, in animal models and cadavers. Clinical skills and knowledge to safe operations are qualified.

Inclusion Criteria:

• rectal cancer patients, confirmed by the endoscopic biopsy;
• curative rectal cancer in clinical stage with resectable lesion, the cTNM stage \