Adjuvant chemotherapy for poor-responders to neoadjuvant therapy in locally advanced rectal cancer: does it improve the prognosis?

Background: Colorectal cancer is the first cause of cancer death in developed countries. Although colon and rectal cancers are frequently grouped as a single disease entity, these malignancies have important differences in treatment approaches ; The preoperative radio-chemotherapy combination has become the standard for tumors of the middle and lower rectum, improving local control. But unlike colon cancer, currently there is no compelling evidence of the benefit of adjuvant chemotherapy in rectal cancer. This study examines the role of adjuvant chemotherapy after a neoadjuvant treatment and chirurgy in localy advanced rectal cancer, especially in poor responders to neoadjuvant therapy. Patients and Methods: Using the medical files collected at the medical oncology department at the Hassan II Hospital Center in Fez , Morocco; patients with rectal cancer diagnosed in 2014 through 2019 who received neoadjuvant CRT(concomitant radio chemotherapy) and surgery with or without AC(adjuvant chemotherapy) were identified. Kaplan-Meier analysis, log-rank tests were used to assess survival. Results: A total of 90 patients were identified; 70 received AC and 20 did not (observation [OBS] group). Median overall survival(OS) of the general population was 40 months, CI 95% = [25-56], the median disease-free survival (DFS) was 17 months,CI 95% = [7-26]. In the analysis of survival according to the ypT and ypN subgroups: the median OS in the ypT1-2 and ypN0 subgroup was higher than in the ypT3-4 or ypN + group (40 months vs 33 months and 44 months vs. 31 consecutive months); DFS was also better in the ypT1-2 and ypN0 group (29 months vs. 11 months (p = 0.05) and 29 months vs. 13 months respectively).The median OS was 40 months for AC and 23 months for OBS (p = 0.036), by against there was no significant improvement in recurrence-free survival. Conclusions: In this population of patients with LARC (localy advanced rectal cancer) treated with neoadjuvant CRT and surgery