Rectal Cancer

Preoperative radiation therapy (RT) is utilized for locally advanced (e.g., T3 or N+) rectal cancer and may be delivered with either conventional fractionation over 5–6 weeks with concurrent chemotherapy, or “short-course” hypofractionated RT alone delivering 25 Gy in 5 fractions with or without additional sequential preoperative chemotherapy. Randomized trials have established general equivalence between these two approaches in the preoperative setting. However, questions remain regarding optimal patient selection and the role of short-course RT with the modern paradigms of total neoadjuvant treatment and nonoperative management. In contrast to the other chapters of this section, neither IMRT nor SBRT has well-defined roles in the treatment of rectal cancer; short-course RT is delivered to typical pelvic volumes usually with 3D-CRT.