Proteomic Approach Using Matrix-assisted Laser Desorption/Ionization Tandem Time-of-flight (MALDI-TOF/TOF) of Tumor Response in Rectal Carcinoma After Radiochemotherapy

Treatment for locally-advanced rectal adenocarcinoma includes preoperative radiochemotherapy before surgery with total mesorectal excision in order to reduce tumor infiltration, facilitate oncologic surgery and improve survival. About fifty percent of these patients are good responders i.e. their tumor infiltration reduces in the rectal wall and regional lymph nodes in order to be graded ypT0 to T2 N0 after pathologic assessment (so called downstaging). At the opposite, bad responders (ypT3-4 and/or N+) are not sensitive to standard preoperative radiochemotherapy, and their survival is poor than good responders. Until now, response to preoperative radiochemotherapy cannot be anticipated before pathological assessment of surgical specimen. Proteomic analysis of sera from good and bad responders to preoperative radiochemotherapy could allow identification of early biomarkers of tumor response, and subsequently adaptation of treatment to increase preoperative treatment efficiency and survival in most patients.