This screening method is cheap and easy to perform. Studies of its effectiveness show conflicting results. This may be because women do not always examine their breasts thoroughly enough, perhaps because they are not confident about their ability to do so.

In addition to being able to detect cancer, a woman who examines her breasts regularly may spare herself unnecessary diagnostic procedures by being able to tell her doctor which lumps have been in her breasts for years and require no new examination. On the downside, breast self-examination may lead to anxiety and unnecessary surgery when benign lumps are discovered.

Begin with a careful visual examination of your breasts while standing in front of a mirror. With your arms in different positions (at your sides, raised over your head, hands on your hips, and chest muscles tensed), note whether the breasts are symmetrical and look for any changes in shape, depressions or bulges, dimples, sores, color of the skin and area surrounding the nipples, and direction in which the nipples point.

Start the physical examination while taking a shower or bath. (Wet soapy breasts are easier to examine because there is less skin resistance, and any lumps or thickening are easier to detect than when the breasts are dry.) Place one hand behind your head, and with the other, carefully examine the breast, feeling for any unusual lumps, thickening, or other changes. Repeat on the other side.

Next lie down on your back with one arm tucked behind your head and a pillow placed under your back; use your fingers to carefully examine all areas of the breast.

One method is to move in circles from the outer portion toward the nipple. (Some women find it easier to go from top to bottom rather than in circles; what's important is to make sure you feel all portions of each breast.) Again, you're feeling for any changes or unusual lumps, thickening, or swelling.

The US Task Force concludes that since the evidence on the usefulness of breast self-examination is inconclusive, there is no reason to urge all women to start examining their breasts. On the other hand, there is no reason for women who already practice breast self-examination to stop. In contrast, the American Cancer Society recommends that women examine their breasts every month starting at age 20.

Breast self-examination is a simple, 5-minute routine that the American Cancer Society urges all women over the age of 20 to perform monthly. This should be done during the week following menstruation, when breasts are less likely to be swollen and tender. After menopause, simply pick a date that is easy to remember, such as the first of the month. Any unusual swellings, lumps, sores, nipple discharge, or other changes should be brought to your doctor's attention as soon as possible.

Clinical Breast Exam. Virtually all experts agree that women aged 40 and over should have their breasts examined annually by a physician. The US Task Force also suggests that women with a family history of breast cancer start having the examinations earlier, for example, at age 35; and the American Cancer Society recommends that women aged 20 to 40 have their breasts checked by a physician every three years.