HALO Test

The HALO Breast Pap Test is a non-invasive way of retrieving breast duct cells for pathologic examination. It is NOT a diagnositc test (meaning it will not find a cancer int he breast) but is only used as another way to assess a woman's risk of developing breast cancer in the future. Suction cups are applied to the breast (similar to a breast milk pump) and fluid is obtained from the ducts at the nipple. Approximately 2/3 of the women will have fluid obtained (so 1 in 3 women will not have fluid for examination) and the cells can look normal, hyperplastic, atypical and very rarely frankly cancerous. Hyperplastic cells raises a woman's risk by ~1.5-2x above her known risk (as assessed by the Gail or Tyrer-Cusick models) and atypical cells raise her risk by 4-5x. If cancerous cells are found, advanced imaging must be done to determine where the cells originated. The HALO Breast Pap can be done on any woman over 30-35 years of age and is typically done yearly (just as the cervical Pap test is done).

The HALO test is a way to obtain fluid from the nipple which then can be analyzed to see if there are any abnormal, or atypical cells. Cellular atypia is a risk factor for the future development of breast cancer, and patients who have atypia usually are followed more closely. The HALO test is not a substitute for mammogram or other imaging as it is not meant to diagnose breast cancer - it is a way to determine if a woman might be at increased risk and therefore might need additional imaging. The HALO test is typically used in women under the age of 40, who are not yet undergoing routine screening with mammography.

I use the HALO test fairly often in my practice. It is true that approximately 50% of women will produce fluid. Those that do not produce fluid are considered to have had a normal test, and it is unlikely that they have any abnormality of their milk ducts. If fluid is produced, it is sent for cytology evaluation to see if there are abnormal cells present. Some studies have suggested that if a condition called atypia is present, it has the same significance of atypical ductal hyperplasia found on needle biopsy, which leads to an increased risk of breast cancer in the future.

As the women undergoing the HALO test are often younger than 40 and not undergoing routine mammogram screening, if a patient has atypia found on the HALO test, I would likely recommend that she begin screening, possibly with ultrasound and MRI in addition to mammogram, earlier than age 40. However as pointed out by Dr. Bone, this can open up a whole host of other issues, including radiation exposure and false positive test results.

It is important to remember that the HALO test is not meant to detect breast cancer or to be a screening test for breast cancer. It is a form of risk assessment, meant to help us sort out if a woman should undergo screening when she normally would not. I generally do not recommend that the HALO test be performed on women over age 45.

The HALO test is meant to be used as a risk assessment tool, not a cancer detection test - it primarily meant for women under the age of about 40 (in whom routine mammography is not performed). The idea is that if there are abnormal cells lining the milk ducts, they may be detected in the fluid obtained from the test. If there are abnormal cells, that generally signifies an increased risk of developing cancer, and additional testing (perhaps MRI) may be indicated.

When properly performed, as many as 50% of women will not produce fluid with the HALO test, and in young women, this is considered a "negative" result (no abnormality). However with the normal aging process, there can be atrophy of the milk ducts, so that in women over the age of 40-50, no fluid might be due to changes related to age, and not necessarily a negative result. In addition, the HALO test will probably not pick up abnormal cells even if a cancer is present if the tumor is in the outer aspects of the breast. Lobular cancer (as it is not growing initially in the milk ducts) also will not likely be picked up with the HALO test.

The HALO test is not for everyone and again it is important to stress that this test is not meant to be a screening test for breast cancer, and is not a substitute for clinical and self-examination as well as routine imaging such as mammogram (and ultrasound / MRI if indicated). However when used appropriately it can be helpful to provide some counseling to young women regarding their risk.