Cancers

CANCER PREVENTION AND TREATMENT

Many cancer risk factors are avoidable. Preventing cancer by attention to diet and by quitting or never starting smoking are the most significant strategies to reduce cancer risk. Prevention of cancer is being investigated in clinical trials on dietary patterns (high intake of vegetables and fruits; low intake of saturated fats) and dietary constituents such as vitamins, minerals, and soy. Future progress may depend partly on strategies such as chemoprevention—the use of natural or synthetic substances to prevent cancer cells from forming, progressing, or recurring. For example, the antiestrogen hormone tamoxifen has been shown to reduce the risk of developing breast cancer by 50 percent among women at high risk for this disease. It also has been shown to reduce the risk of developing a new primary breast cancer in the opposite breast among women with a history of breast cancer. Chemopreventive agents also are being investigated for prevention of colon, rectum, prostate, and lung cancers.

SCREENING AND EARLY DETECTION

Mammography has been shown to reduce breast cancer mortality among women over the age of fifty, and Pap smear screening has dramatically reduced mortality from cervical cancer. In addition, there is growing evidence that fecal occult blood testing and endoscopic screening significantly reduce mortality from colorectal cancer. Identification of mutations is becoming an important tool for identifying individuals at high risk of various cancers. For instance, DNA repair-gene mutations (e.g., MSH2, PMS1) have been associated with a higher risk of colon cancer, as have mutations in the tumor suppressor genes BRCA1 and BRCA2 in breast cancer. Although it is believed that inherited risk for cancer accounts for a small proportion of total cancer cases each year, identifying this risk may help researchers determine how cancer develops and progresses, and may provide a tool for targeting prevention or treatment strategies.

Prognosis is dependent on the type of cancer diagnosed, the stage of the disease at the time of diagnosis, and the effectiveness of currently available therapy. Surgery, radiation, chemotherapy, hormonal therapy, and immunologic therapy form the basis of modern cancer treatment. Surgery is generally the treatment of choice for localized tumors, although radiation often is an appropriate alternative. Lasers are being used for small noninvasive tumors of the skin, cervix, and throat. Radiation therapy is often recommended as primary therapy (e.g., for Hodgkin's disease and early stage tumors of the head and neck), and is an important adjunct to lumpectomy for the treatment of breast cancer. Radiation therapy also plays an important role in the symptomatic management of patients with advanced cancer (e.g., bone or brain metastases). In contrast to surgery and radiation, chemotherapy is a systemic, rather than local, therapy, because the drugs are distributed throughout the body. Chemotherapy generally is required to treat advanced cancers that are not amenable to surgical removal or radiation therapy. Chemotherapy is often used after surgery (adjuvant therapy) to reduce the risk of relapse. The most common indication for adjuvant chemotherapy is following surgery for localized breast or colorectal cancer.

Hormone therapy represents a very important category of cancer treatment for breast cancer (tamoxifen and raloxifene) and prostate (androgen blockers) cancer. In addition, immunotherapy (also called biologic therapy) is being used to boost the immune system to fight cancer cells. Monoclonal antibodies are one type of immunotherapy that can be used to fight specific cancer cells or to carry chemotherapeutic agents to a tumor. Interferon is another immunotherapy that has shown promise in slowing the growth of tumors. Each of these treatments has advantages and disadvantages, and should be discussed with a physician.

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Author Info: HOWARD L. PARNES, DARRELL ANDERSON, The Gale Group Inc., Macmillan Reference USA, New York, Gale Encyclopedia of Public Health, 2002

This feature is for informational purposes only and should not be used to replace the care and information received from your healthcare provider. Please consult a healthcare professional with any health concerns you may have.