MammaPrint Feasibility in a Large Tertiary Urban Medical Center : An Initial Experience

Abstract EN

Background.

The MammaPrint (MP) diagnostic assay stratifies breast cancer patients into high- and low-risk groups using mRNA analysis of a 70-gene profile.

The assay is validated for assessment of patients with estrogen receptor positive or negative tumors less than 5 cm with 3 or fewer malignant lymph nodes.

TargetPrint (TP) is an assay for assessing estrogen, progesterone, and HER2-neu receptor status based on mRNA expression.

A potential limitation of these assays is that they require an evaluation of fresh tissue samples.

There is limited published experience describing MP or TP implementation.

Methods.

Over 10 months, 4 breast surgeons obtained samples from 54 patients for MP/TP analysis.

The samples were analyzed by Agendia Labs.

The tumors were independently evaluated for receptor status using immunohistochemistry (IHC).

Retrospectively, we identified patients who were assessed by MP/TP during this period.

Patients who underwent OncotypeDx evaluation were also identified.

Results.

Of the 54 patients receiving MP, 4 were found ineligible for MP risk assessment because >3 lymph nodes were found to be malignant.

Out of all eligible patients, 14/50 (28%) had samples whose quantity of tumor was not sufficient for analysis (QNS).

Out of eligible patients with tumors <1 cm, 7/8 (88%) had QNS samples.

7/42 with tumors ≥1 cm (17%) had QNS samples.

Nine patients had discordant receptor results when evaluated by IHC versus.

TP.

Of patients who also underwent OncotypeDx testing, 6/14 (43%) had discordant results with MP.

Conclusions.

This study indicates that using MP/TP assay is feasible in a tertiary care center but there may be utility in limiting MP testing to patients with tumors between 1 and 5 cm due to high likelihood of uninformative results in subcentimeter tumors.

Further study is needed to explore the discordance between oncotype and MP results.