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Upon completion of the chapter, the reader will be able to:
Identify the risk factors for colorectal cancer.
Outline preventive and screening strategies for individuals at average and high risk for colorectal cancer.
Recognize the signs and symptoms of colorectal cancer.
Describe the treatment options for colorectal cancer based on patient-specific factors, such as stage of disease, age of patient, genetic mutations, and previous treatment received.
Outline the pharmacologic principles for agents used to treat colorectal cancer.
Develop a monitoring plan to assess the efficacy and toxicity of agents used in colorectal cancer.
Educate patients about the adverse effects of chemotherapy that require specific patient counseling.
Colorectal cancer is one of the four most common cancers diagnosed in the United States and includes cancers of the colon and rectum. In 2018, an estimated 140,250 new cases of colorectal cancer are expected to be diagnosed, with an estimated 50,680 deaths expected, making colorectal cancer the second leading cause of cancer-related deaths in the United States.1 The prognosis is primarily determined by the stage of disease with the majority of patients with early stage (I or II) disease cured. Treatment options for colorectal cancer include surgery, radiation, chemotherapy, and targeted molecular therapies.
EPIDEMIOLOGY AND ETIOLOGY
Colorectal cancer occurs more frequently in industrialized regions such as North America and Europe, while the lowest rates are seen in less-developed areas, suggesting that environmental and dietary factors influence the development of colorectal cancer. In addition to environmental factors, colorectal cancers develop more frequently in certain families, and genetic predisposition to this cancer is well known.
The incidence of colorectal cancer in men is approximately 1.3 times greater than observed in women. Overall, colon and rectal cancers make up approximately 12% of all cancer diagnoses in men and women in the United States. The median age at diagnosis is 67 years with very few cases occurring in individuals younger than 45 years of age.2 Age appears to be the biggest risk factor for the development of colorectal cancer with 57% of cases diagnosed in adults older than 65 years of age.
Although still the second leading cause of cancer death, mortality rates for colorectal cancer have declined over the past 30 years as a result of better and increasingly used screening modalities and more effective treatments.
In addition to age, dietary or environmental factors, inflammatory bowel disease, and genetic susceptibility increase the risk of colorectal cancer. Table 91–1 lists well-known risk factors for developing colorectal cancer.
Table 91–1Risk Factors for Colorectal Cancer