A Global, Integrated, Personalized, Stage-related, Multimodal Therapeutic Approach for Rectal Adenocarcinoma Based on Organ Sparing and Mininvasivity

Accurate staging with Pelvic MRI, CT scan, PET total body have to be performed before local excision in order to exclude false positive mesorectal lymph nodes. Subsequent Wait and See (W\&S) approach could be proposed.

Participants with cT2N0 rectal tumors are typically candidates for upfront surgical resection. The investigators propose an alternative approach based on experimental chemoradiotherapy (spCRT). Literature suggests that pathologic complete response (pCR) rates after CRT are significantly higher than the 25% described for intermediate-advanced tumors. The investigators will assess clinical complete response (cCR) or complete metabolic response (cMR) through a multidisciplinary restaging process, including MRI, PET, thorax-abdomen CT scan, ERUS, and rectoscopy. In participants achieving cCR or cMR, a Watch and Wait (W\&S) strategy or Local Excision/Transanal Minimally Invasive Surgery (LE/TAMIS) may be proposed to avoid the physical and psychological consequences of major surgery, followed by a rigorous surveillance program.

Tumors will be initially treated with standard CRT (stCRT). Patients who reach cCR-cMR at restaging they are already candidates to sparing approaches with W\&S/LE/TAMIS according to Multicentric Resarch Study Protocol