Cancer encompasses a group of diseases that are marked by rapid, uncontrolled cell proliferation and a conversion of normal cells to a more primitive and undifferentiated state.1,2 Large tumors, or neoplasms, may form from excessive cell proliferation. Although some types of tumors are well contained (benign), malignant tumors continue to proliferate within local tissues and can possibly spread (metastasize) to other tissues in the body. The term cancer specifically refers to the malignant forms of neoplastic disease, which can often be fatal, as tumors invade and destroy tissues throughout the body. However, benign tumors can also be life-threatening; for example, a large benign tumor may produce morbidity and mortality by obstructing the intestinal tract or by pressing on crucial central nervous system (CNS) structures. Cancer cells, however, are unique in their progressive invasion of local tissues and their ability to metastasize to other tissues.1
Cancer ranks second to cardiovascular disease as the leading cause of death in the United States.3 There are many different types of cancer, and malignancies are classified by the location and the type of tissue from which the cancer originated.1 For instance, cancers arising from certain epithelial tissues (e.g., skin, gastrointestinal lining) are labeled as carcinomas; cancers arising from connective tissues (e.g., bone, striated muscle) are labeled as sarcomas. In addition, cancers associated with the formed blood elements are connoted by the suffix -emia (e.g., leukemia is the cancerous proliferation of leukocytes). Many other descriptive terms are used to describe various malignancies, and certain forms of cancer are often named after a specific person (e.g., Hodgkin disease, Wilms’ tumor). It is beyond the scope of this chapter to describe all the various types of malignancies. You may want to consult a pathology text or similar reference for more information about the location and morphology of particular forms of cancer.1,2,4
The exact cause of many cases of neoplastic disease is unknown. However, a great deal has been learned about possible environmental, viral, genetic, and other elements, or carcinogens, that may cause or increase a person's susceptibility to various types of cancer. Conversely, certain positive lifestyles, including adequate exercise, a high-fiber diet, and the avoidance of tobacco products, may be crucial in preventing certain forms of cancer. Of course, routine checkups and early detection play a vital role in reducing cancer mortality.
When cancer is diagnosed, three primary treatment modalities are available: surgery, radiation treatment, and cancer chemotherapy. The purpose of this chapter is to describe the basic rationale of cancer chemotherapy and to provide an overview of the drugs that are currently available to treat specific forms of cancer. You may routinely work with patients undergoing cancer chemotherapy. For reasons that will become apparent in this chapter, these drugs tend to produce toxic effects that directly influence physical therapy and occupational therapy procedures. Therefore, this chapter should provide ...