Volume 18, No. 2, Spring 2010
By Jean Talbert, M.D.
This past November, the U.S. Preventive Services Task Force (USPSTF) presented new guidelines for breast cancer screening. The guidelines are the opinion of a large group of scientists and clinicians and are intended to be a minimum standard for average risk, asymptomatic women. They were developed from large population-based studies evaluating statistical risks and benefits.
Although the timing was unfortunate–coinciding with Congressional health care reform debates–there is no evidence that this is part of a conspiracy to eliminate health services for women.
The new guidelines recommend:
The change in guidelines took many of us by surprise. Breast cancer is the second leading cause of cancer death among women. The majority of these cancers are detected by screening mammography. A significant number are detected by women themselves; either by chance or during self breast exam. Early detection and advanced treatment have both contributed to declining mortality rates from breast cancer over the last two decades.
The cost-effectiveness of screening mammograms in women under 50 was called into question for several reasons.
Yet some studies have shown that screening beginning at age 40 can lower breast cancer mortality by 16 percent.
Unfortunately, breast cancer screening does carry some risks. False positive rates are high and approximately 11 percent of mammograms require additional evaluation. Ninety percent of the time, the area of concern is benign. Fifty percent of women will have one false positive for every 10 that they have performed. Rates of false positives are highest in women under 50. False positives generate considerable anxiety plus discomfort from additional procedures, more radiation exposure and increased cost.
Another risk of screening is over-diagnosis. That’s when early breast cancer is detected, but is unlikely to affect life expectancy. Over-diagnosis is greatest in women over age 75 or among those with a life expectancy of less than 10 years.
Some women may find the risks of screening to be acceptable, others may not. Each woman should be counseled individually regarding her particular risk/benefit situation.
The major factors in breast cancer risk are age, genetic predisposition and prior history of chest radiation for cancer. Thirteen percent of women will be diagnosed with breast cancer by age 90, the majority during their 60s. Women who carry a breast cancer gene have up to a 60 percent lifetime chance of developing breast cancer. Additional risk factors include family history, age over 30 at first birth, late menopause, use of post menopausal hormone replacement therapy, alcohol use, high bone density, dense breast tissue, and history of breast biopsy.
Several screening tools have been developed to help to determine each woman’s individual risk. The widely-used Gail model can be accessed on-line at www.cancer.gov/bcrisktool/. While no assessment tool is perfect, they are helpful in determining screening protocols.
Unfortunately, these tools do not consider risk factors such as environmental exposures. For example, women on Cape Cod have a 15 to 20 percent higher risk of developing breast cancer than elsewhere in the state. Those who have lived here the longest (15-20 years) have the greatest risk. Therefore providers should be aware of these unique local factors.
Women should discuss all this with their clinicians, touching on personal preference as well as potential risks and benefits.
(Dr. Talbert is a board certified OB/GYN specialist practicing with Cape Obstetrics, Midwifery & Gynecology in Falmouth and Sandwich, 508-457-0088.)