MedWire News: Tumor size, tumor-nipple distance, and human epidermal growth factor receptor gene (HER)2 amplification could help identify patients suitable for nipple-sparing mastectomy, US researchers report.

The oncological safety of nipple-sparing mastectomy is controversial. Therefore, Elena Brachtel (Massachusetts General Hospital, Boston) and colleagues reviewed nipple pathology in patients currently undergoing mastectomy to provide guidance as to which nipples might be preserved without compromising patient safety.

They evaluated 316 consecutive mastectomy specimens (232 therapeutic, 84 prophylactic) with grossly unremarkable nipples by coronal sections through the entire nipple and subareolar tissue to a depth of at least 0.5 cm below the skin level.

As reported in the Journal of Clinical Oncology, 71% of nipples from therapeutic mastectomies showed no pathologic abnormality, 21% had ductal carcinoma in situ (DCIS), invasive carcinoma (IC), or lymphovascular invasion (LVI), and 8% had lobular neoplasia. Spread of carcinoma to the nipple occurred most frequently in breasts with ductal carcinoma in situ.

Most nipples with invasive carcinoma showed direct extension of invasive tumor into the retroareolar region and the nipple papilla. Ductal carcinoma in situ was also found to spread along ductal structures in the nipple by direct extension.

In univariate analysis, tumor size, tumor-nipple distance, HER2 amplification, histologic grade and lymph node involvement influenced the likelihood of nipple involvement. However, only tumor size, tumor-nipple distance and HER2 amplification remained significant predictors in a multivariate model.

The sensitivity for the retroareolar tissue, defined as the tissue approximately 0.3 cm beneath the skin of the nipple-areolar complex, to indicate involvement of the nipple by carcinoma was 80%, and the negative predictive value was 96% for the retroareolar tissue to indicate absence of nipple involvement.

Of note, none of the 84 prophylactic mastectomies showed nipple involvement by IC or DCIS.

“Nipple-sparing mastectomy may be suitable for selected cases of breast carcinoma with low probability of nipple involvement by carcinoma and prophylactic procedures,” remark Brachtel and co-authors.

They conclude: “A retroareolar en-face margin may be used to test for occult involvement in patients undergoing nipple-sparing mastectomy.”

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