MOLECULAR SUBTYPES OF BREAST CANCER AND IMMUNOHISTOCHEMISTRY FEATURE OF TUMOR AS A PREDICTIVE FACTORS OF NIPPLE INVOLVIMENT FOR CARCINOMA

Fernando Tochet, Adriana Worschech, Renato Z. Torresan, Giuliano Mendes DuarteNatalie Rios Almeida, Maria Virginia Thomazini, André Oliveira, Luciana Moreira,

Introduction: The knowledge of predictive factors of nipple involvement in breast cancer patients is importante to decide for nipple sparing mastectomy. However, some factors, as molecular subtype of breast cancer, is unknowed whether they are associated with disease in the nipple. The aim of this study was to evaluate whether molecular subtypes determined by immunohistochemistry can be a predictive fator of occult nipple involvement. Methods: A prospective study was performed with 64 consecutive women who had undergone mastectomy or central segmentectomy. Patients with inflammatory breast cancer, carcinoma clinically involving the nipple, Paget´s disease of the nipple and skin involvement were excluded. The nipples were removed from the breast specimens and submitted to rigorous histopathology exam separately. The nipple was sectioned in half in the sagital direction and each half was cut every 2-3mm in the direction perpendicular to the first cut. Nipple involvement was considered in situ or invasive carcinoma. The tumor was submitted to immunohistochemistry exam for: estrogen receptor (ER), progesterona receptor (PR), HER-2 and ki67. It was considered luminal A: ER and PR positives, HER-2 negative and ki67 < 20%; luminal B: ER positive, PR negative, HER-2 negative and ki67 > 20% or HER-2 positive; HER-2: ER and PR negative and HER-2 positive and triple negative (TN): ER/PR/HER-2 negatives. The statistical analyze used Fisher test, Mann-Witheny test and significance level of 5%. Results: The occult nipple involvement rate was 12.5% (8/64). The molecular subtypes of breast cancer were luminal A 39%, luminal B 35.9%, HER-2 9.4% and TN 15.7%. The occult nipple involvement rate in each subtype was: luminal A 8%, luminal B 13%, HER-2 16.7% and TN 10%. There was no significant difference in nipple involvement rate among molecular subtypes (p=0.556). Our data suggest that the molecular subtypes of breast cancer are not predictive fator of nipple involvement for cancer.

Keywords: Occult nipple involvement; Nipple sparing mastectomy; Molecular subtypes.