Background and Objective: Surgery is still considered the mainstay of treatment of locally advanced rectal cancer (LARC). Nevertheless, "curable" disease may still pose a great risk for both local and distant relapses. Since the early eighties of the past century, we have witnessed mounting evidence supporting the multi-modality approach to tackle this disease effectively. The multi-modality approach is variable between different positive trials. In this review, we discuss the treatment evolution of LARC, highlighting the key differences between the different contemporary strategies utilized. Based on current evidence, we sought to define distinct patient subgroups and to propose a treatment algorithm that best fits patient's risk. Methods:We conducted a literature search through PubMed and Google Scholar. Eligible papers were phase 2/3 trials [in organ preservation (OP), observational and retrospective studies were also acceptable] published in English. We used keywords such as "locally advanced rectal cancer", "perioperative therapy in rectal cancer", "short course radiotherapy", "chemoradiation in rectal cancer", "interval to surgery", "Neoadjuvant therapy", "Organ preservation" and "Total neoadjuvant treatment [TNT]".

IntroductionThe aim of this study is to identify factors that may predict the response of locally advanced rectal cancer tumors (LARC) to neoadjuvant chemoradiotherapy (CRT) and to evaluate the effect of circulating lymphocytes on pathological tumor response.MethodsThis retrospective study included neoadjuvant CRT-treated, LARC-diagnosed patients at the Rambam Health Care Campus in Haifa, Israel. CHAID analysis, t-test, χ2 test, and ROC curve analyses were performed to explore the association between pathological complete response (pCR) and several factors including patient demographics, tumor characteristics, type of treatment, and levels of circulating lymphocytes measured on a weekly basis.ResultsOut of 198 patients enrolled in the study, pCR was achieved in 50 patients (25%). ROC curve and CHAID analyses showed that absolute lymphopenia was significantly associated with lower pCR rates (p=0.046 and p=0.001, respectively). Other factors that were found to have a significant impact were radiation therapy type (p=0.033) and tumor distance from the anal verge (p= 0.041).ConclusionAn absolute decrease in the level of circulating lymphocytes during preoperative CRT to LARC is associated with poorer tumor response to treatment and thus may serve as a predictive biomarker for treatment resistance.