Radiotherapy and Its Side Effects: Chapter 1 - Introduction

PART II

Chapter 1

Introduction (cont'd)

Radiotherapy has been used for both curative and adjuvant cancer treatment for many years. Adjuvant therapy refers to auxiliary/additional treatment for cancer; adjuvant radiotherapy is usually given after surgery or in conjunction with chemotherapy when a potential risk of relapse remains. Radiotherapy can also be given before surgery to reduce the mass of tumor to be removed.

Roughly speaking, 60% of all cancer patients receive radiotherapy, thus, radiotherapy might not be necessary for all cancer cases. For example, according to a scientific report in the New England Journal of Medicine, it was indicated that children with the most common form of leukemia can safely forego radiation therapy if they are treated with chemotherapy regimens tailored to their individual needs. The conclusion was based on a clinical trial involving 498 patients with acute lymphoblastic leukemia.  Nearly 94 percent of the patients were still alive 5 years after treatment, a result that compares favorably with other treatment studies.

An overly simplified schematic representation of how radiation works is shown in Fig. 2.1. Basically, radiation therapy works by damaging the DNA of cancer cells and hampering these cells from replicating. The damage to cancer cells is caused by radiation, which directly or indirectly breaks up the DNA chain. The indirect damage comes from free radicals including hydroxyl radical (HO^·), superoxide  (O₂^-), hydrogen peroxide (H₂O₂), peroxyl (ROO^·) and alkoxyl (RO^·) radicals, collectively called reactive oxygen species (ROS).  

Fig. 2.1   Schematic representation of how radiation works

© Jiajiu Shaw, 2020

Disclaimer: This blog is written solely for informational purposes. It does not constitute the practice of any medical, nursing or other medical professional health care advice, diagnosis, or treatment. All contents posted are extracted from the book, "SIDE EFFECTS OF CHEMOTHERAPY AND RADIOTHERAPY", prepared by Dr. Jiajiu Shaw, Dr. Frederick Valeriote, and Dr. Ben Chen.