Exploring the attenuating effect of amifostine on neoadjuvant radiotherapy with concurrent use of irinotecan for locally advanced rectal cancer: a retrospective cohort study of 154 cases

Background and purpose: Rectal cancer is one of the malignant tumors that seriously harm human health in the world, ranking third in incidence and second in mortality. With the development of social and economic level, the incidence and mortality of colorectal cancer in China are increasing, and China becomes one of the countries with high incidence of colorectal cancer disease in the world. The recommended treatment for locally advanced rectal cancer is neoadjuvant chemoradiotherapy combined with surgery, which greatly improves the prognosis of patients. However, intestinal adverse reactions such as diarrhea caused by neoadjuvant chemoradiotherapy are increased, and some patients are forced to delay or interrupt treatment due to serious side effects. Amifostine is a broad-spectrum normal cell protective agent, which has good protective effect against various radiochemotherapy toxicity. We conducted a retrospective analysis of patients with locally advanced rectal cancer who received neoadjuvant radiotherapy combined with irinotecan concurrent chemotherapy to investigate whether concurrent use of amifostine alleviated gastrointestinal and hematological toxicities. Methods: A retrospective cohort analysis was used in this study. Clinical data of patients with locally advanced rectal cancer who received neoadjuvant chemoradiotherapy at the Affiliated Cancer Hospital of Fudan University during the period of discharge from January 1, 2018 to December 31, 2019 were retrospectively collected. The patients were divided into 2 groups by whether amifostine was used during the same period. The main purpose of the study was to analyze whether amifostine can reduce gastrointestinal and hematological toxicities, and secondary objectives included whether amifostine could alter tumor marker levels, mesorectal fascia invasion (MRF) positive rate, extramural vascular invasion, positive rate of EMVI and pathological complete response (pCR). Using SAS9.4 statistical software, the normality test was carried out for continuous variables. The rank sum test of Wilcoxon was performed when the diarrhea grade did not conform to normal distribution. Analysis of variance was performed for intra-group comparison, and Wilcoxon rank sum test was performed for inter-group comparison. Because of the imbalance between groups, the difference between the two groups was compared using a generalized linear model. This study strictly followed the STrengthening the Reporting of OBservational stu