Applied Genomics

Mammostrat is indicated for postmenopausal, node-negative breast cancer patients who receive a positive estrogen receptor immunohistochemistry test. The test is currently being offered by AmeriPath’s Molecular Profiling Institute (MPI), a CLIA-certified reference laboratory located in Phoenix, Arizona that is trained in staining and interpreting Mammostrat biomarkers. After estrogen receptor status has been established, Mammostrat can be ordered by the referring pathologist or oncologist. Go to How to Order for information on ordering Mammostrat testing.

The five Mammostrat biomarkers that make up the test are listed below along with a brief description of their potential function in the cell:

	p53 is known to play a central role in cell cycle regulation and mutations in p53 contribute to tumor formation.
	HTF9C is co-expressed with proteins that are involved in DNA replication, implicating HTF9C in DNA replication and cell cycle control.
	CEACAM5 is normally expressed in embryonic tissue and is aberrantly expressed in some cancers.
	NDRG1 is expressed under conditions of hypoxia and other stresses. It may have a role in helping tumors survive under the hypoxic, stressful environment confronting aggressive tumors.
	SLC7A5 is involved in nutrient transport. Over-expression of SLC7A5 could help sustain the high growth rate of cancer cells by increasing a cell’s ability to consume nutrients.

For Mammostrat testing, either eight sections (four micrometers thick) or the un-sectioned, formalin-fixed, paraffin-embedded tumor tissue should be sent to MPI. A specimen transport kit can be ordered from MPI to facilitate shipping of slides or blocks and to ensure the safe arrival of patient samples.

Mammostrat testing is performed by staining the supplied sections and appropriate control tissue with the five Mammostrat antibodies. A trained pathologist will then score the stained slides according to established criteria. A "0" for negative staining or a "1" for positive staining for each antibody will be entered into the AGI algorithm to calculate a "Risk Index." The Risk Index value will be used to classify the patient as low, moderate, or high likelihood of breast cancer recurrence. The ordering pathologist will receive a report similar to the sample report shown here. The Mammostrat report will list the staining result for each antibody, the Risk Index category (i.e. low, medium, or high) and an interpretation of what the score means for the patient.

Pathologists, oncologists and patients should use the Mammostrat test results in conjunction with other clinical information to help select amongst treatment options.