5.2.1. Radiation Therapy

Radiation therapy (RT) is the application of ionizing radiation to treat cancer. Cancer cells are more sensitive to DNA damage than normal tissue cells; this characteristic provides the therapeutic effect [38]. It is estimated than 50% of the population with cancer can benefit from this therapy [38]. For colorectal cancer, RT is used as a neoadjuvant treatment to improve patient prognosis, heightening the overall survival rate, diminishing the local recurrence rate, and improving the quality of the surgical procedures [39].

Besides some side e ffects—such as incontinence of the anal sphincter or urinary tract problems, vaginal dryness, and sexual dysfunction, among others—related to neoadjuvant RT, new techniques have focused e fforts on modulating the beam intensity and improving the beam precision and development of delivery systems for encapsulated radionuclides (brachytherapy) [39,40].
