University of California San Francisco
Helen Diller Family Comprehensive Cancer Center

Screening Guidelines

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General Breast Cancer Screening

Recommendations regarding screening with mammography in the U.S. range from having annual mammograms starting at age 40, to having mammograms every 2 years from ages 50-74. Importantly, for women 40-49, the US Preventive Task Force Guidelines call for patients and their physicians to make an individual decision, taking into account family and personal history of cancer as well as factors like a history of previous biopsies, age at menarche, age of child bearing, intake of alcohol, smoking habits, diet, weight, prior radiation therapy and/or hormone replacement therapy. Of course, paramount to good decision making is understanding the benefits and risks of screening. Screening has benefits, but it also has some limitations. It is important for clinicians and patients to be aware of these so that we make the most of the information we get from screening.

For Women Ages 50 to 74

Evidence from clinical trials has shown that women age 50-74 receive the greatest benefits of early detection through screening. As women get older, breast cancer is more common. Breast cancer is made up of several types, some that are aggressive and grow quickly, and some that grow less quickly. Mammography makes the biggest impact on women with slow and moderate growth tumor, which are most common for women in this age group. As you get older, you are more likely to develop very slow growing tumors, which may not benefit from early detection. Therefore, you are less likely to benefit from screening, especially if you have other serious medical conditions such as heart disease or diabetes which are more likely to cause mortality. Additionally, the U.S. Preventive Task Force Guidelines showed that, screening every other year has just about as much benefit as screening annually since many tumors found in women in this age range are slower growing and finding them early doesn't make a difference in terms of treatment. Since screening more frequently would not result in a better outcome, it is all right to stretch the interval between mammograms to 1.5- 2 years. This is consistent with how mammographic screening is conducted in Europe.

For Women Ages 50 and Under

Women in their 40's need to be informed that the chance of being called back for additional studies or a biopsy is pretty high while the chance of actually having a cancer is relatively low. If 2000 women are screened every year for 10 years, 1100 will have a call back and possibly a biopsy, but probably only 10 cancers will be found, and screening would have saved the life of 1 of the 10. If there is a family history or other risk factors, women should be screened annually in their 40's, but should discuss their risk with their health care practitioner as they might also consider prevention options such as chemoprevention, surgical prophylaxis and/or lifestyle changes. Screening does have some benefit in this age group, but it is small. Women should weigh the pros and cons and make an informed decision. How often to screen is controversial. Women in this age group are more likely to have faster growing tumors so it may make sense to screen annually if you are going to screen.

Women of All Ages

The woman herself is the most familiar with how her own breasts feel and can often recognize a change. Rapidly growing tumors are more common in young women, but can arise at any age. If you develop a change or a lump in the breast, bring it to the attention of a medical professional.

Photo credit: Bonnie N. Joe, MD, UCSF