The Ethics Committee for Biomedical Research of the Jikei Institutional Review Board approved the protocol of this study [30-249(9270)]. Between 2010 and 2014, 110 patients with T3 lower rectal cancer without lateral lymph node metastasis, 80 years of age or younger, who underwent curative resection at four Jikei University Hospitals were enrolled in this retrospective study. Of these patients, 94 underwent neither preoperative CRT nor intensive chemotherapy after surgery: 47 patients who did not receive OAC for a pathological diagnosis of stage II cancer and 47 patients who did receive OAC for a pathological diagnosis of stage III cancer. The remaining 16 patients received intensive chemotherapy after surgery without preoperative CRT (Table I). All patients (n=110) underwent total mesorectal excision (TME) with bilateral autonomic nerve preservation without lateral pelvic lymph node dissection. Disease-free survival (DFS) and the received treatments were retrospectively compared between groups. The medical records of all patients were reviewed and classified according to the Japanese Classification of Colorectal Carcinoma [3]. According to this classification, T3 corresponds to invasion of the subserosa.
Oral adjuvant chemotherapy after surgery
For 6 months after surgery, patients with stage III disease (n=47) received oral S-1 (Taiho Pharmaceuticals Co., Ltd., Tokyo, Japan) or capecitabine (Xeloda; Hoffmann-La Roche, Basel, Switzerland), whereas patients with stage II disease (n=47) received no adjuvant chemotherapy.
Intensive chemotherapy after surgery
The intensive chemotherapy group (n=16) received oxaliplatin-based combination regimens (infusional 5-fluorouracil and folinic acid plus oxaliplatin [FOLFOX], S-1 (Taiho Pharmaceuticals Co., Ltd., Tokyo, Japan) plus oxaliplatin [SOX], capecitabine plus oxaliplatin [CapeOX]) for 6 months after surgery.
Treatment schedule
All patients were followed for 5 years; during this period, physical examinations, routine blood analyses, and serum CEA measurements were conducted every two months after surgery. CT was performed every 6 months or when a patient’s serum CEA value was higher than the normal level of 5.0 ng/ml. Colonoscopy was performed every year or when a stool sample was positive for blood. Positron emission tomography (PET) or PET/CT was occasionally employed to detect occult metastasis for patients who had equivocal conventional imaging studies.
Statistical analysis
Continuous variables are expressed as the mean and range. The Wilcoxon rank-sum test was used for the comparison of continuous variables, and a chi-squared test was used for the comparison of categorical data. DFS after surgery was examined by the Kaplan-Meier method and by log-rank analysis. Variables affecting postoperative recurrence were analyzed using the Cox proportional hazards regression. A p-value of less than 0.05 indicated significance. All data were analyzed with IBM SPSS Statistics, version 24.0 (IBM Japan, Ltd, Tokyo, Japan).