Screening digital mammography is a low-dose x-ray examination of the breast that is performed on women with no complaints or symptoms of breast cancer (asymptomatic). The goal of screening mammography is to detect breast cancer when it is still too small to be felt by a physician or the patient. Research has shown that the early detection of small breast cancers by screening mammography greatly improves a woman’s chances for successful treatment. For example, if breast cancer is caught and treated while it is still confined to the breast ducts, the cure rate is close to 100%.
Who Should Receive a Screening Digital Mammogram?
The American Cancer Society recommends that women begin receiving screening mammograms every yearbeginning at age 40 and continuing for as long as a woman is in good health. Since the number of breast cancer diagnoses rises significantly when women reach their forties, annual screening mammography can help detect breast cancers at an early stage, when treatment is most likely to be successful.
In addition, women younger than 40 who are at high risk of developing breast cancer (i.e., they have a strong family history of breast cancer or test positive from BRCA gene mutations), should ask their physicians about beginning annual screening mammograms earlier than age 40, as early as age 25 in some cases.
Why is a Screening Mammogram Important?
Mammography is currently the only exam approved by the U.S. Food and Drug Administration (FDA) to screen for breast cancer in women who do not show any signs or symptoms of the disease. Mammography can detect approximately 80% of breast cancers. If a screening mammogram indicates a possible abnormality, women will be asked to return for additional testing, typically additional mammographic views and/or ultrasound. The need for additional imaging is closely related to image quality, operator experience, high-quality appropriately maintained equipment and the experience of the radiologist interpreting the exam. The chance of being “recalled” for additional imaging ranges from 5%-20% nationwide. There is little difference in cancer detection or outcomes between the lowest and highest ranges and the difference typically reflects the experience of the practice. Images interpreted in general radiology facilities by general radiologists typically run in the 10-20% range whereas images interpreted by specialists typically run in the 5-10% range. At Carolina Breast Imaging Specialists we continuously monitor our results and have consistently been able to achieve high cancer detection rates while recalling only 5-6% of our screening patients. This may not seem like much but those “unnecessary” recalls are very distressing and costly to patients while doing very little to accomplish the goal of finding early breast cancer. If further imaging confirms or reveals an abnormality, the woman may be referred for biopsy to determine whether she has breast cancer. There are significant differences between specialized practices like Carolina Breast Imaging Specialists and general radiology practices at this level as well. Specialists are able to reduce the number of biopsy recommendations so less women without cancer have to go through the biopsy process.
While screening mammography can detect most breast cancers, on average it can miss up to 20% of cancers. There are some patient populations, such as young women with dense breast tissue, where mammography can miss almost half of the cancers. This is particularly important to keep in mind when a woman or her doctors detects and abnormality on a breast exam. In these cases, even if the mammogram does not reveal any abnormality, additional imaging, usually with ultrasound, is important to determine if a significant abnormality may be “hiding” on the mammogram.
Breast cancer may not be visible on a screening mammogram if:
- The cancer is very small
- The cancer is in an area that is not easily imaged with mammography (such as in the axilla (the underarm region) or deep in the breast.
- The cancer is obscured by other shadows and/or dense breast tissue.
Even though mammography may miss some breast cancers, it is well proven to find many early breast cancers and is primarily responsible for the great improvement in breast cancer survival we have seen over the past decades. Therefore, it is important for women 40 years of age and older to get a mammogram each year and have current mammograms compared with previous films to determine whether cancer is beginning to develop.