[The Different Indications and Treatment Effect between Preoperative Chemotherapy and Preoperative Radiotherapy for...

We evaluated the difference in effectiveness between preoperative radiotherapy (RT) and chemotherapy (C) as part of multimodal therapy for locally advanced rectal cancer. In the RT group, 43 patients were enrolled and preoperative radiotherapy was performed with 42.6 Gy for 4 weeks. In the C group, 16 patients were treated with preoperative chemotherapy consisting of mFOLFOX6/XELOX plus bevacizumab for 3 months. All 43 tumors in the RT group were located in the lower rectum. The C group was composed of 9 in the lower rectum and 7 in the middle or upper rectum. The C group was more advanced than the RT group in terms of depth of invasion, lymph node metastasis, and tumor diameter. The histological treatment response was better after RT (7 with little, 10 with a minor, 24 with a major, and 2 with a complete response) than after C (10 with little, 4 with a minor, 1 with a major, and 1 with a complete response). The tumor reduction ratio by colonography showed 36.5% after RT and 28.7% after C. CEA was reduced by 47.2% after RT and 45.2% after C. Though RT is more effective for local lesions than C, C is expected to be preferred as the local and systemic therapy for locally advanced rectal cancer with pelvic organ involvement or lateral lymph node metastases.