Objective: The study was prospectively designed as a single-arm, single-institution prospective trial of pre-operative concomitant hyperfractionated radiotherapy (HART) with co-administration of chemotherapy based on 5-fluorouracil (5FU) in patients with T2/N+ or T3/any N resectable mid-low primary rectal cancer. The aim of the study was to assess the safety and efficacy of accelerated HART with concurrent 5FU-based chemotherapy in patients with locally advanced rectal cancer.
Methods: Patients with resectable locally advanced (≥T3 or N+) rectal cancer were eligible. The patients received total dose 42 Gy in 28 fractions of 1.5 Gy, two times daily, with at least 8 h of interval, with concurrent chemotherapy: 325 mg m-2 of 5FU (bolus) on Days 1-3 and Days 16-18 (except for cN0 patients for whom only one cycle on Days 1-3 was prescribed). The primary end point included tolerance, post-operative complication rate and pathological response rate. The secondary end points included locoregional relapse-free survival, metastasis-free survival and overall survival.
Results: Out of 53 enrolled patients; 2 did not undergo surgery. Of the 51 patients evaluable for pathological response, there were 8 (15.6%), 20 (39.3%), 18 (35.3%) and 5 (9.8%) patients with tumour regression grade 0, 1, 2 and 3, respectively. Downstaging of the primary tumour and lymph nodes was observed in 22 (43%) and 25 (49%) patients, respectively. The primary tumour ypCR (ypT0) rate was 15% (8/51). The nodal ypCR rate for cN+ patients was 60% (21/35). The total ypCR (ypT0N0M0) rate was 11% (6/51). Toxicity included: Grade 3 diarrhoea (4/51, 7.8%), Grade 2 diarrhoea (22/51, 43.1%), Grade 2 leukopenia (7/51, 13.7%), Grade 2 neutropenia (6/51, 11.7%) and Grade 1 thrombocytopenia (3/51, 5.9%). No Grade 4 toxicity was reported. Nine patients (18%) presented with post-operative complications (during the 3 months after surgery). There were 6 locoregional relapses (11.8%) and distant metastasis occurred in 11 patients (21.6%). The 2-year cumulative locoregional relapse-free survival, metastasis-free survival and overall survival was 87%, 79% and 89%, respectively.
Conclusion: The proposed pre-operative HART with co-administration of 5FU had acceptable toxicity profile and provided satisfactory rate of ypCR. This created rationale to initiate a Phase III randomized study that was registered under ClinicalTrials.gov Identifier: NCT01814969. Advances in knowledge: The results of this research show that responders to pre-operative radiochemotherapy have favourable outcome. Tumour regression grade as prognostic clinical feature holds the promise of better classifying patients at high risk of local and systemic recurrence and this issue may be an interesting objective for future research.