NAF Clinical Information

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Breast Cancer Development

To appreciate the concept of screening for benign breast disease, and the analogy to the Pap test, it is important to understand the disease and its course of development. Virtually all breast cancer originates in the epithelial cells that line the interior of the milk ducts in the breasts. Like cervical cancer, breast cancer progresses through identifiable stages of development.

Development of Atypia Cells - Breast Cancer Stages

Like cervical cancer, breast cancer typically grows slowly, taking, on average, 8 years before it can be detected by mammography, or up to 10 years before the lesion is palpable. The inability of current breast screening methods to detect cellular changes at an early stage of development, as the Pap test does for cervical cancer, is one reason for the lack of significant reduction in the death rate of breast cancer.

Breast and Cervical Cancer Deaths US

A major difference between the cervical Pap test and NAF cytology is that most asymptomatic women do not secrete NAF, or secrete acellular samples. These are normal states and confer the lowest risk of developing breast cancer. With the cervical Pap test, it may be reported that the sample is inadequate for analysis if very few cells are present. In NAF cytology this is reported as an acellular sample, which confers the lowest relative risk among patients who are secretors. Multiple studies have confirmed that women who do not produce a NAF sample are at a significantly reduced risk of developing breast cancer, compared to women with abnormal cytology.

Clinical Utility of Risk Assessment Breast Disease

With the understanding that almost all breast cancers begin in the milk ducts, Nipple Aspirate Fluid (NAF) examination allows the determination of benign breast disease, and the attendant increase in relative risk, years before an abnormality becomes visible by imaging or becomes a palpable lesion.

NAF Cytology Enables Early Detection of Cancerous Growth at the Pre-Invasive Stage

The study of NAF to identify high risk women is not new. In 1958, Dr. George Papanicolaou et al described obtaining fluid from the breast milk ducts by suction to analyze cell samples. Just like his procedure for detecting normal versus abnormal cells in the cervix (the "Pap test"), this technique demonstrated the ability to find abnormal cells in nipple aspirate fluid (NAF) from within the breast duct. Dr. Papanicolaou concluded that "cytology of breast secretions was valuable in differential diagnosis of mammary diseases and carcinoma" and that "a cytological diagnosis of malignancy was highly reliable."

Multiple clinical studies involving over 30,000 patients, followed for up to 25 years, all reach the same conclusion: benign breast disease, specifically atypia, confers a significantly higher risk of breast cancer. On average, these clinical studies demonstrate the presence of atypia to mean a woman has a greater than 4X (i.e., 400%) relative risk of developing breast cancer than women who do not produce fluid.

The findings of Wrensch, Petrakis et al and the clinical significance of atypical hyperplasia have been validated through independent studies of samples collected from NAF, fine needle aspiration biopsy, or surgical excision.

Cytologic Assessment-Clinically Validated

An official statement from the American Society of Breast Surgeons reads in part "A variety of techniques exist to obtain cells for examination, including open surgical biopsy, fine needle aspiration (FNA), nipple aspirate fluid (NAF), and ductal lavage. In current studies of surgical biopsy, FNA and NAF report a 5-fold increase in the relative risk of developing breast cancer when cellular atypia is found. Having atypia coupled with a first degree family history of breast cancer confers an 11 to 22-fold increase in relative risk of developing breast cancer."

We have known for decades that atypia is an important breast cancer risk factor, but have lacked a practical way to apply this knowledge to the general asymptomatic population. The primary care setting is the point-of-care where screening must occur, but the breast specialist must manage the high-risk patients. With the advent of a noninvasive, office-based method of collecting NAF, we have the opportunity to enter more high risk women into enhanced surveillance programs earlier, and help them avoid a life-threatening battle with breast cancer.


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