Screening For Breast Cancer

Breast cancer is the most common non-skin cancer and the second most likely to lead to death in women. In the United States, more than 180,000 women are diagnosed with invasive breast cancer each year and more than 40,000 die from the disease. Most breast cancers in the United States are diagnosed as a result of an abnormal screening test. Thanks to a massive public relations campaign, including Walk for the Cure, we all know that breast cancer is easier to cure when caught at an early stage and that screening is the best way to find those early lesions.

Which screening methods are effective and when should a woman start screening? Remember that screening tests are designed to find disease in women without any symptoms. If you do have symptoms such as a lump in your breast, skin changes, pain or nipple discharge, your doctor may recommend tests other than those that I will discuss here.

Some women are at greater risk for developing breast cancer than others. Their risk factors include age, genetic predisposition and exposure to estrogen. Tools are available that can calculate a woman’s breast cancer risk and perhaps help her and her doctor decide how to proceed with breast cancer screening. The Gail Model tool is the most widely used and is available online at www.cancer.gov/bcrisktool/.

Mammograms are the most commonly used breast cancer-screening tool. A study of 1.5 million mammograms showed that 1.6 percent led to breast biopsy and 0.5 percent led to a diagnosis of breast cancer. Several studies have shown a significant reduction in deaths from breast cancer in women between 40 and 69 years old. How often should you have a mammogram? Testing every two years seems to have approximately 80 percent of the benefit of testing every year. Breast cancers grow more quickly in younger women who may require testing more frequently than older women.

Film mammography (x-ray) is the most established and most common form of mammography, but newer approaches are becoming available. Full-field digital mammography captures the image and stores it on a computer. This method may provide a small advantage to women under 50 years old and women with dense breasts. Computer-aided detection (CAD) assists the radiologist by recognizing mammographic patterns and identifying suspicious patterns. This method slightly increases the number of breast cancer cases identified by screening but also increases the number of women called back after mammography for further testing.

Magnetic resonance imaging (MRI) is a relatively new method and has not been studied extensively. In addition, it is very expensive. It seems to be best used in women with a very high risk of breast cancer, as calculated by a model such as the Gail Model. In fact, the American Cancer Society recommends that it only be used in combination with mammography in women with a lifetime risk of breast cancer greater than 20 to 25 percent.

Breast palpation (or feeling the breast) is the simplest screening method available. Clinical breast examination (CBE) is when a health-care provider examines the breast and self-breast examination (SBE) is when the patient examines her own breast. Ten to 15 percent of breast cancers are felt on physical exam but are not seen on mammogram.
At what ages should women receive breast cancer screenings? One study showed that 1,339 women in their 50s needed to be screened to prevent one death from breast cancer, compared to 1,904 women in their 40s. Some experts predict that mammograms be continued as long as a woman has a life expectancy of at least 10 years. Women with a family history of breast cancer should talk with their doctors about special screening requirements and other preventive options, such as genetic testing.

Dr. McMahon, a graduate of Yale University and the University of Pittsburgh School of Medicine, is board certified in Internal Medicine. She is a member of the American College of Physicians and the Allegheny County and Pennsylvania Medical Societies. She is in solo practice in the North Hills of Pittsburgh.