Concurrent Chemoradiation with Concomitant Boost in Locally Advanced Rectal Cancer: A Phase II Study

The aim of this study was to evaluate the pathological response of locally advanced rectal cancer after preoperative concurrent two-drug chemotherapy and intensified radiation therapy (RT) with concomitant boost. Patients with T4 tumor or local recurrence were included. A trial based on two-stage Simon's design was planned. RT was performed with 3D-conformal technique. The dose to the mesorectum and pelvic lymph nodes was 45 Gy (1.8 Gy/fraction). A concomitant boost was delivered to Gross Tumor Volume (GTV) 2 cm margin to a total dose of 55 Gy (2.2 Gy/fraction). The following concurrent chemotherapy was administered: Raltitrexed (3 mg/m(2)) and oxaliplatin (130 mg/m(2)) on days 1, 17, and 35 of RT. Pathological response was evaluated according to the Mandard classification. Toxicities were scored according to the Common Terminology Criteria for Adverse Events v3.0 scale. Eighteen patients (median age=64.5 years) were enrolled. The median follow-up was 22 months (range=2-36 months). After chemoradiation treatment, 16 patients underwent surgical resection (seven anterior resections and nine abdominal-perineal amputation); two patients did not undergo surgery due to early metastatic progression or refusal. R0 resection was achieved in all patients who underwent surgery. Five patients had pathological complete response [27.7%; 95% confidence interval (CI)=9.7-53.5%] and two patients showed only microscopic residual disease (11.1%; 95% CI=0.1-34.7%). Mandard grades 1 and 2 were detected in seven patients (38.9%; 95% CI=17.3-64.3%). Acute grade 3 or more toxicity was found in eight patients (44.4%; 95% CI=21.5-69.2%): one leucopenia-neutropenia, one liver, one skin and five cases of gastrointestinal toxicities. No patient had local tumor recurrence. One-, 2- and 3-year cumulative disease-free survival were 93.8%. One-, 2- and 3-year cumulative overall survival were 92.3%. Concurrent chemoradiation with concomitant boost in patients with advanced rectal cancer allows complete or near-complete pathological response in more than 38% of patients. However, severe acute toxicity was reported in more than one-third of patients.