Mammograms are a screening tool for detecting breast changes. An “abnormal” result can cause worry, but it is important to understand that it does not automatically signify breast cancer. Often, these findings lead to further investigation that ultimately reveals a benign, or non-cancerous, condition.
Prevalence of Abnormal Mammograms
A significant percentage of screening mammograms are initially flagged as abnormal. Approximately 7% to 10% of women are asked to return for additional testing. This number can fluctuate based on factors like a woman’s age or breast density. Despite this seemingly high callback rate, the majority of these abnormal findings are not breast cancer. Only about 0.5% of women who get regular mammograms are found to have breast cancer, as the test is designed to be sensitive, detecting anything unusual, even if harmless.
Decoding Abnormal Mammogram Results
An “abnormal” mammogram result means something on the imaging requires a closer look. Radiologists use a standardized system called BI-RADS (Breast Imaging Reporting and Data System) to categorize findings, ranging from 0 to 6. A BI-RADS Category 0 means the images are incomplete or unclear and additional views are needed. Categories 1 and 2 indicate normal or benign findings, meaning no signs of cancer.
BI-RADS 3 are considered “probably benign,” with a very low chance of being cancerous, typically less than 2%. These often warrant short-interval follow-up imaging. Higher categories, BI-RADS 4 and 5, indicate suspicious findings for cancer, necessitating further evaluation like a biopsy. The appearance of a mass, its shape, margins, and the presence of calcifications are details radiologists consider when assigning a BI-RADS category.
Navigating Follow-Up Care
When a mammogram result is abnormal, further diagnostic tests are typically recommended. A diagnostic mammogram involves more detailed and magnified views of the area of concern. An ultrasound of the breast is also a common follow-up procedure, using sound waves to create images. Ultrasound is particularly useful for distinguishing between a fluid-filled cyst, which is typically benign, and a solid mass, which might require further investigation.
In some cases, a breast Magnetic Resonance Imaging (MRI) may be performed, particularly for women with dense breast tissue or a high risk of breast cancer. MRI uses magnets and radio waves to produce detailed images, and it can help detect small lesions that mammography might miss. If findings remain suspicious after these additional imaging tests, a biopsy may be recommended. A biopsy involves removing a tissue sample from the suspicious area for examination under a microscope to determine if cancer cells are present.
Common Reasons for Abnormal Findings
Numerous non-cancerous factors can lead to an abnormal mammogram, making further evaluation necessary. Dense breast tissue is a frequent cause, appearing white on a mammogram, similar to how masses or tumors appear, and can obscure potential abnormalities. Younger women often have denser breast tissue.
Benign breast conditions like cysts and fibroadenomas are common. Cysts are fluid-filled sacs that can appear as smooth, round masses on a mammogram. Fibroadenomas are non-cancerous solid lumps composed of glandular and fibrous tissue, often appearing as distinct, smooth-edged masses. Calcifications, which are tiny calcium deposits, can also be detected; while many are benign, certain patterns may require additional assessment. Hormonal changes, prior breast surgeries, or even artifacts from products like deodorant can also lead to findings requiring a closer look.