Efficacy and Safety of High Dose Radiotherapy for the Treatment of Locally Advanced Rectal Cancer

Abstract

To explore the feasibility of high dose chemoradiotherapy in treating patients with locally advanced rectal cancer. Patients with stage II/III rectal adenocarcinoma who had received pelvic radiation with a total dose ≥60Gy for curative intent in our center between April 2006 to July 2017 were studied retrospectively. Survival rate were analyzed and toxicity was evaluated according the National Cancer Institute Common Toxicity Criteria 3.0. A total of 48 patients were included, with a median age of 59.5 years (IQR 46.5-71). 19 (39.6%) patients were diagnosed as stage II, and 29(60.4%) were stage III. Of which, 42 (87.5%) patients had their tumor located within 5cm from the anal verge. High-dose radiotherapy were given using the technique of three-dimensional conformal radiation therapy or intensity modulated radiation therapy. Patients who gave up surgery before treatment received one course high dose radiotherapy (gross tumor volume (GTV) 60-70Gy/30-35f, median dose 66Gy). Patients had residual tumor after neoadjuvant chemoradiotherapy (1st: GTV 45-50Gy/25f) but insisted on non-operative treatment had received a second courses of radiotherapy (2nd: GTV 30/15f). Median total dose was 80Gy and the median interval between the 2 courses was 71 days. All patients received fluorouracil-based concurrent chemotherapy. Median follow-up was 30 months. Six patients (12.5%) had local progression, and the median time of local progression was 11 months (range, 8-22 months). Of which, four underwent salvage surgery. Six patients (12.5%) developed distant metastasis. The 3-year local recurrence-free survival (LRFS) and distant metastasis-free survival (DMFS) were 85.0% and 78.7%, while the 3-year progression-free survival (PFS) and overall survival (OS) were 68.5% and 88.1%, respectively. No significant difference was observed in 3-year LRFS, DMFS, PFS and OS between patients with different stages or patients receiving one or two courses of radiotherapy. Only one patient developed grade 3 radiodermatitis, while no level 4-5 acute radiation related adverse reaction was reported and chronic radiation proctitis that need medical intervention was hematochezia occurred in 3 (6.3%) of the patients. High dose radiation combined with chemotherapy have shown good survival outcome with acceptable short-term and long-term side effect, and might be considered as a non-invasive alternative for rectal cancer patients who refuse surgery.