Adjuvant chemotherapy for rectal cancer

Abstract

We read with interest the metaanalysis by Anne Breugom and colleagues about the role of adjuvant chemotherapy for patients with locally advanced rectal cancer treated with preoperative (chemo)radiotherapy. Adjuvant fl uorouracil-based chemotherapy was found not to improve overall survival, disease-free survival, or distant recurrences for patients with rectal cancer receiving neoadjuvant treatment. The authors stated that noncompliance to adjuvant chemotherapy was a serious problem in studies of adjuvant chemotherapy in patients with rectal cancer after preoperative (chemo)radiotherapy and surgery; less than 50% of the patients in the EORTC 22921 trial and CHRONICLE trial completed all cycles of chemotherapy. Thus, there is a possibility that survival in patients receiving adjuvant chemotherapy was no better than in patients who did not because they received inadequate courses of adjuvant chemotherapy. It is important that the authors, if possible, compare survival of patients who received the full course of adjuvant chemotherapy with that of patients who underwent observation. Furthermore, the authors could compare the survival of patients who received inadequate cycles of adjuvant chemotherapy with that of patients who underwent observation. The patients included in the metaanalysis had ypNM stage II and III disease, and the specifi c compliance to adjuvant chemotherapy in this subgroup was unclear. In terms of disease-free survival and distant recurrence, the authors found that adjuvant chemotherapy might benefi t patients with a tumour located 10–15 cm from the anal verge. It is not clear why 5-cm intervals were chosen to separate the diff erent parts of the rectum and how the authors found that the tumours located 10–15 cm from the anal verge benefi ted most from adjuvant chemotherapy. We think it is possible and more reasonable to acquire the optimal cut-off value through receiver operating characteristic curves or other methods when identifying who might really benefi t from adjuvant chemotherapy. It would also be interesting to do further analysis of distant metastasis incidence in diff erent part of the rectum, and then evaluate the true value of adjuvant chemotherapy. Some retrospective studies have shown that adjuvant chemotherapy might still be valuable for patients with rectal cancer treated with preoperative (chemo)radiotherapy, although these results c ontradict the conclusion by Breugom and colleagues. The contradictory fi ndings suggest that there might be a subgroup of patients who would benefi t from adjuvant chemotherapy, and the challenge now is to defi ne this subgroup.