The role of MRI for breast cancer screening

MRI or magnetic resonance imaging uses radio waves and magnetic fields to provide images of organs and other internal structures that may not be clearly seen with other tools like X-ray or CT. In recent years, doctors have begun to explore its benefit in screening women with a higher risk of breast cancer. Breast cancer is the 2nd most common cause of cancer death in women. In 2013, there were 232,340 new cases of invasive breast cancer, 64,640 new cases of carcinoma insitu and 39,620 breast cancer related deaths.  “Every woman should begin screening mammograms at age 40 and continue them as long as they are in good health. –American Cancer Society” Why is MRI recommended for high risk women? MRI has a 91% better sensitivity for identifying cancerous breast masses when compared to traditional mammography. So why isn’t it used for everyone? In reality, most women with an average risk of the disease will only need a mammogram. This way, the sensitivity of the test will not identify benign lesions or other spots that could raise the risk for additional testing, biopsies and unnecessary fear. MRI diagnostics are reserved for women with the highest risk of the disease and therefore need the most sensitive screening tools available. Screening mammograms, while beneficial for many women, can be less specific or sensitive for women with complicating factors like dense breast tissue when used alone. Some specific types of breast cancer, such as lobular carcinoma may be difficult to visualize with traditional screening mammography as well. Other factors that can classify a woman as high risk for breast cancer include:

• Women with a known or suspected BRC1 or BRC2 genetic mutation
• A history of chest radiation therapy between the ages of 10 and 30
• Women with a greater than 20% risk of developing breast cancer

Remember that for high risk women, MRI isn’t the only tool that’s needed to gather a full picture of breast health. Annual MRI and mammography is currently recommended. My risk is intermediate or in the middle. Should I have an MRI? Right now, the American Cancer Society has not found sufficient evidence to recommend MRI screening for women with an intermediate risk. Women with an intermediate risk include:

• Women with a personal history of invasive/in situ carcinoma
• Women with a personal history of lobular neoplasia or atypical hyperplasia
• Women with a 15-20% lifetime risk of developing breast cancer

The average woman has less than a 15% chance of developing breast cancer. These women do not need screening MRIs. What other methods can assess my risk of developing breast cancer? There are a variety of tools your doctor uses to determine your breast cancer risk. If you are unsure about your risk, make an appointment with your healthcare provider to discuss it. Some providers use what’s called the Tyrer-Cuzick model to determine your risk. This tool evaluates:

• Age
• Body mass index (BMI)
• Hormonal factors
• Hereditary factors (including cancers in first and second degree relatives)

A note about BRCA1 and 2 Genetic mutations can further raise your risk for breast cancer. Called the BRCA1 OR BRCA2, this genetic mutation is responsible for about 10% of all breast cancer cases. Women who inherit a mutated gene have a 60-80% risk of developing breast cancer. In addition, women with BRCA1 have a 33% higher risk of developing ovarian cancer. Screening and counseling are available for women with a family history of breast or ovarian cancer or known BRCA mutation in the family. BRCA1 associated tumors tend to have smooth margins and appear more benign on mammogram. They are more aggressive, often high grade and tend to be larger at diagnosis.