Cancer Prevention and Screening

The best way to control cancer is to prevent it. The most effective cancer prevention measure is smoking cessation. According to the National Cancer Institute, cigarette smoking causes 87% of lung cancer deaths and is responsible for most cancers of the larynx, oral cavity and pharynx, esophagus, and bladder. The risk of cancer with smoking is cumulative. Stopping at any age is beneficial; at first the risk plateaus, and then it may even decrease over time.

A sedentary lifestyle and obesity increase the risk of many cancers such as breast, colon, endometrial, and prostate cancers. Exercise might decrease the risk of breast cancer. One study, the Iowa Women's Health Study, suggests that intentionally losing weight might reduce the risk of obesity-related cancers.

There is an increasing interest in using medications to prevent cancer. Studies have examined the use of aspirin to decrease the risk of colon cancer in patients with colon adenomas (benign noncancerous growths) with promising short-term results. However, at least one randomized prevention study using very low-dose aspirin did not show a preventive effect. Some epidemiological cohorts suggest that participants taking statins (drugs that lower cholesterol levels) might also have a reduced risk of cancer.

Another effective method of decreasing cancer mortality is to use screening tests to detect cancers at early stages, when they have the highest chances of cure. The best-established screening test is the Papanicolaou test, familiarly known as Pap smear. This test scrapes a few cells from the cervix of the uterus and analyzes them for signs of malignant transformation (change in cellular appearance suggestive of the development of cancer tendency). This test has dramatically reduced the mortality from cervical cancer in developed countries. In developing countries, cervical cancer is still very much a concern, and large efforts to screen these women are being undertaken. The risk of cervical cancer is highest in younger women. It is associated with infections with human papilloma virus. Women age 70 years and older in good health who have had three normal Pap smears in a row can stop getting Pap smears. However, postmenopausal women are also at risk for endometrial cancer, so regular gynecological visits should be continued.

A simple but effective cancer screening test is an annual skin examination by a dermatologist. This allows the removal of common skin cancers such as basal cell carcinoma and squamous cell carcinoma. These very frequent cancers are due to sun damage, rarely metastasize, and are usually cured by simple surgical resection. If ignored, however, they can be locally invasive, causing local damage, pain and dys-function. More critically, a yearly skin examination allows the early detection of melanoma. Melanoma is a tumor in which stage makes a dramatic difference in prognosis. A melanoma less than 1 millimeter thick at the time of surgery has very little chance of having spread and will most likely be cured. A thicker melanoma that has spread to the lymph nodes has a much worse prognosis. There is some evidence that melanomas have a worse prognosis in older people. It is unclear whether this is because they are thicker or ulcerated when detected or is due to another reason.

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