Breast Masses

1

What are evidenced-based components of breast screening?

Screening mammography has the most evidence to support it as a breast cancer screening tool.

A screening study has value when:

• a.

  The incidence of the disease is high.

• b.

  The risks from the screening study are low.

• c.

  There are disease-specific treatments that can be administered when the disease is caught early that will improve the patient outcome more than waiting to treat the disease if it is identified later.

Screening mammography detects breast cancer before it causes clinical symptoms. The incidence of breast cancer is high; one in eight women will develop breast cancer in their lifetime. Screening mammography is relatively low risk and low cost. The most common risk is false-positive findings that might require further imaging or biopsy. There are many excellent treatments for breast cancer, including surgery, chemotherapy, hormonal therapy, biologic therapy, and radiation therapy. Breast cancers treated at an early stage do better than breast cancers that are diagnosed at a late stage.

2

When should routine screening mammography begin?

There is quite a bit of controversy surrounding the optimum mammography screening schedule for women at average risk of developing breast cancer. There is controversy about when screening should start, how often it should be done, and when it should stop. The options include:

• a.

  Starting screening between age 40 and 50 years

• b.

  Screening interval of 1–2 years

• c.

  Stopping screening between age 75 and 90 years

The greatest benefit in screening programs occurs when a patient goes from no screening to some screening. Further modifications to the screening schedule will provide smaller incremental benefits in disease diagnosis. These incremental benefits are accompanied with a proportional increase in risk. Each woman can identify the risk:benefit ratio at a level comfortable to her. At minimum, a woman at average risk should begin screening no later than 50 and no less often than every 2 years, continuing until she is at least 75 years old.

For women at high risk because of family history or other circumstances, screening may begin earlier, but not before age 30, and be done more often, but not more frequently than annually.

3

What about breast self-examination or clinical breast exam?

Many large studies done in multiple countries have failed to show a survival benefit to regularly scheduled breast self-examination. Women should be familiar with their breasts and report any changes to their healthcare provider.

Clinical breast examination done by a healthcare provider has also been shown to create more false positives than true positives and not improve outcomes.

4

Does a normal or negative mammogram guarantee that no cancer is present?

No. Mammography has a false-negative rate of at least 15%. For a breast cancer to be detected on mammography, it must have tissue characteristics that are different from the surrounding tissue. Some tumors, particularly lobular carcinoma, invade the surrounding breast tissue in a way that does not alter the characteristics of the breast tissue. Such tumors are often not visible on mammogram.

5

What is the role of screening magnetic resonance imaging (MRI) as an adjunct to mammography?

American Cancer Society guidelines published in 2007 recommend screening MRI for women with a >20% lifetime risk of developing breast cancer. This includes women who have a known gene mutation that predicts for the development of breast cancer, a strong family history of breast or ovarian cancer that suggests a genetic mutation, and women who have received chest radiation for Hodgkin’s disease as teenagers or young adults. Gene abnormalities that predict for early breast cancer include BRCA1 , BRCA2 , Li-Fraumeni, Cowden, or Bannayan-Riley-Ruvalcaba syndromes. With expanded genetic testing now being easily available, additional gene mutations are being identified regularly and should be included in high-risk screening recommendations.

MRI is quite sensitive for identifying breast cancer but is criticized for having a lower specificity that leads to additional imaging and biopsies. MRI should be used in conjunction with mammography and is not an independent screening modality for breast cancer.