Efficacy of neoadjuvant chemoradiotherapy combined with surgery for rectal mucinous adenocarcinoma

Abstract

Objective To explore the efficacy of neoadjuvant chemoradiotherapy (NACRT) combined with surgery for rectal mucinous adenocarcinoma. Methods The retrospective cohort study was conducted. The clinical data of 313 patients with locally advanced rectal carcinoma who underwent NACRT combined with surgery at the Fujian Medical University Union Hospital between January 2008 and December 2013 were collected. Among the 313 patients, 32 and 281 patients were respectively allocated into the mucinous adenocarcinoma (MA) group and non-mucinous adenocarcinoma (NMA) group. Irradiation range included primary rectal lesion and pelvic lymph drainage, the upper bound is the fifth lumbar vertebra lower edge, both sides beyond true pelvic brim 1.5 cm, and the lower bound is the anus verge. Chemotherapy regimens included fluorouracil capecitabine and capecitabine combined with oxaliplatin. Operation was carried out after 6-8 weeks at the end of radiation according to the standard of total mesorectal excision (TME). Postoperative chemotherapy was conducted using the same preoperative regimen for 6 months. Observation indicators: (1) the sensitivity comparison of NACRT between the 2 groups [ypTNM stage, T downstaging, N downstaging, pathological complete response (PCR), rectal cancer regression grade (RCRG)] ; (2) long-term outcomes comparison after neoadjuvant chemoradiotherapy between the 2 groups. Follow-up using telephone interview, correspondence and outpatient examination was conducted once every 3 months within postoperative 2 years, once every 6 months at postoperative 3 years and once every year at postoperative 4 years up to June 30, 2015 and the end of follow-up (tumor recurrence and metastasis or death). Follow-up included physical examination, carcinoembryonic antigen (CEA) and CA19-9 test, chest X-ray and hepatic ultrasound and colonoscopy. Chest computed tomography (CT) and abdominal magnetic resonance imaging (MRI) or bone emission computed tomography (ECT) were conducted and PET/CT was conducted when necessary. Measurement data with normal distribution were represented as ±s, and comparison between groups was analyzed using an independent sample t test. Measurement data with skewed distribution were represented as M (range). Ordinal data were analyzed by the Mann-Whitney U test. Comparisons of count data were done using chi-square test. The Kaplan-Meier method was used to draw the survival curve and assess survival rate. The Log-rank test was used to compare survival. Results (1) The sensitivity comparison of NACRT between MA and NMA groups: number of patients in stage ypTNM 0, Ⅰ, Ⅱ and Ⅲ was 2, 5, 12, 13 in the MA group and 56, 65, 77, 83 in the NMA group, respectively, with a statistically significant difference between the 2 groups (Z=4.845, P 0.05). (2) The long-term outcomes comparison after neoadjuvant chemoradiotherapy between the 2 groups: 259 patients were followed up for a median time of 39 months (range, 6-90 months), 54 were dead and 72 had tumor recurrence or metastasis. The 3-year overall survival rate and 3-year tumor-free survival rate were 82.3%, 73.8% in the MA group and 84.4%, 78.0% in the NMA group, respectively, with no statistically significant difference between the 2 groups (χ2=0.399, 0.359, P>0.05). Conclusion The NACRT combined with surgery for rectal cancer has also benefited mucinous rectal carcinoma, and it is equivalent in the overall survival of patients with non-mucinous adenocarcinoma. Key words: Rectal neoplasms; Mucinous adenocarcinoma; Neoadjuvant therapy; Multivariate analysis