CHAPTER 14 - Chemotherapy and radiation therapy for cancer

Abstract

The havoc of cancer is widely observed across the globe. Although the extent of affecting the population in developed and developing regions is different due to distinct contributing factors, however, treatment modalities across the world remain the same. Cancer therapy uses different treatments, either alone or in combinations, for treating cancer patients. These therapies include surgery, chemotherapy (CT), radiotherapy (RT), and recently immunotherapy. The utility of each therapy depends upon the type of cancer, grade, and stage. CT employs diverse drugs to target cancer cells, and RT uses energy beams for targeting the cancer cells. There are several classes of chemotherapeutic drugs, based on their mechanism of action, used in the treatment of cancer, such as antibiotics, mitotic inhibitors, alkylating agents, topoisomerase inhibitors, antimetabolites, corticosteroids, and signaling inhibitors. RT uses high-energy beams such as gamma rays, x-rays, protons, or electron beams to treat the tumor. Radiation-induced generation of reactive oxygen species (ROS) and DNA damage is a vital contributor to the radiation-induced killing of cancer cells. During treatment, resistance to CT and RT is a common event and is the major hurdle for cancer treatment and thus reduces the overall therapeutic index of contemporary treatment modalities. Cancer cells acquire several molecular alterations during the treatment, which might lead to the development of chemoresistance and radioresistance in cancer cells. Despite several technological advancements, chemo and radioresistance are still the major challenges, and thus relapse cases in cancer patients occur frequently, which reduces the quality of life. In this chapter, we have explained two primary cancer treatment modalities, CT and RT, in an elaborate manner, which are employed for almost all cancer treatments. Furthermore, we have taken into consideration the problem of resistance development in chemotherapy and radiotherapy in cancer patients, along with the significant contemporary advancements in cancer therapy to overcome the problem of resistance in treatment.