The American Cancer Society (ACS) estimates that, in the year 2005, ~145,290 people will be diagnosed with colorectal cancer and ~56,290 patients will die of the disease.1 Colorectal cancer is the third most commonly diagnosed cancer and the second most common cause of cancer death in the United States.1 Although many health organizations recommend that colorectal cancer screening begin at the age of 50 for people at average risk, <50% of people 50 years old or older get tested.1
Colorectal cancer usually develops slowly over a period of many years. It may begin as a noncancerous polyp that develops into cancer. More than 95% of colorectal cancers are adenocarcinomas, which evolve from glandular tissue.1
Ninety percent of cases of colorectal cancer occur in patients over age 50, and ~75% of these cases occur in patients with no known medical risk factors for developing the disease.2 Examples of some of these risk factors1,2 are as follows:
Signs and Symptoms
In many cases, there are no signs or symptoms during the early stages of this cancer. When present, they may include the following:
Patients should be encouraged to consult a physician to discuss any of these symptoms.
Colorectal cancer can be highly curable if detected in the early stages. Individuals 50 years old or older should be screened regularly. Those with known risk factors should begin extensive testing and screening even earlier. The ACS recommends that patients over age 50 have a fecal occult blood test annually and a sigmoidoscopy every 5 years.2
Screening tests available include the following2:
Individuals diagnosed with colorectal cancer may receive surgery, chemotherapy or radiation, or a combination of these therapies. The type of treatment is dependent upon the stage of the cancer, whether the cancer is a recurrence, and/or the individual's general health status.
Examples of Some New Pharmacologic Therapies
Oxaliplatin (Eloxatin, Sanofi- Aventis) was first approved by the FDA in 2002 for the treatment of advanced colorectal cancer, and it is now approved as first-line treatment when combined with 5-fluorouracil (FU) and leucovorin (LV).4 Oxaliplatin, used in combination with infusional 5-FU/LV, is indicated for adjuvant treatment of stage III colon cancer patients who have undergone complete resection of the primary tumor. The indication is based on an improvement in diseasefree survival, but with no demonstrated benefit in overall survival after a median follow-up of 4 years.5
In 2004, the FDA approved 2 new pharmacologic treatments for advanced colorectal cancer. These agents, bevacizumab (Avastin, Genentech) and cetuximab (Erbitux, ImClone Systems Inc and Bristol-Myers Squibb) are part of the drug class known as monoclonal antibodies. Bevacizumab is indicated for use in combination with intravenous 5-FU-based chemotherapy as first-line treatment of patients with metastatic carcinoma of the colon or rectum.6 Cetuximab is indicated for use in combination with irinotecan for the treatment of epidermal growth factor receptor-expressing, metastatic colorectal carcinoma in patients who are refractory to irinotecan- based chemotherapy.7 Cetuximab is the first monoclonal antibody approved to treat this type of cancer.8
Preventing Colorectal Cancer
Although the exact cause of colorectal cancer still is not known, there are many measures that can be taken to prevent it. The most powerful tool is routine screening, because this cancer can be diagnosed in the early stages, thus increasing the chance for survival. Other measures that can aid in preventing or decreasing the risk of developing this cancer include the following:
Studies in the prevention of colorectal cancer suggest that risks can be lowered by the following factors3,9:
Although there are many treatments for colorectal cancer, the most effective strategies are early detection and preventive measures to lessen the possibility of developing the disease. Pharmacists should remind and encourage patients to get screened regularly and to consult their physicians when needed. For more information, one should visit the American Cancer Society Web site at www.cancer.org or the National Cancer Institute Web site at www.cancer.gov.
Ms. Terrie is a clinical pharmacy writer based in the northern Virginia area.
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