Role of Radiation Therapy in Rectal Cancer Treatment

Introduction to Radiation Therapy

Preoperative radiotherapy is the standard of care for locally advanced rectal cancer, reducing local recurrence rates and having less toxicity than postoperative radiotherapy, as recommended by the European Society for Medical Oncology 1, 2

For very early tumors, local procedures such as transanal endoscopic microsurgery may be appropriate without radiation, according to the National Comprehensive Cancer Network 2, 3
For early favorable cases, surgery alone using total mesorectal excision technique is appropriate, as suggested by the American Society of Clinical Oncology 2, 4
For most cT3 tumors without threatened circumferential resection margin and some cT4 tumors, preoperative radiotherapy followed by TME is recommended, based on guidelines from the European Society for Medical Oncology 2, 4
Short-course radiotherapy followed by immediate surgery is a convenient and low-toxicity option, as reported by the American Society for Radiation Oncology 2, 5

Total Neoadjuvant Therapy, which includes neoadjuvant chemotherapy and either short-course radiation or long-course chemoradiotherapy, has emerged as an important treatment approach, according to the National Cancer Institute 1, 8
Chemotherapy delivered after radiation is preferred based on the OPRA phase II randomized trial, which showed higher rates of TME-free survival at 3 years, as recommended by the American College of Radiology 8
Long-course chemoradiotherapy is preferred over short-course radiotherapy based on the RAPIDO trial showing lower rates of locoregional failure, as suggested by the European Society for Radiotherapy and Oncology 8

Modern radiation techniques should be used to reduce toxicity, as recommended by the American Association of Physicists in Medicine 7

Preoperative treatment is preferred over postoperative treatment due to decreased toxicity and improved efficacy, according to the European Society for Medical Oncology 6, 9, 2
Combinations of 5-FU with other cytostatics or targeted biological drugs have shown higher pathologic complete response rates but also increased toxicity, as reported by the American Society of Clinical Oncology 2, 4