Immunophenotyping of male breast cancer - Experience at a tertiary care centre

Male breast cancers (MBCs) are uncommon and account for 1% of all breast cancers. Medical conditions that increase the estrogen to testosterone ratio are implicated as the risk factors. Morphologically similar, but MBCs have biological differences compared with female breast cancer (FBC).

The present study was aimed to examine the immunophenotype of MBC, subsequent molecular subtypes, their association with clinicopathological features, and prognosis.

We analyzed clinicopathological features of 42 cases of MBC, and classified them according to molecular classification using immunohistochemistry (IHC). This is the second largest study from India.

Median age of patients was 61 years (age range: 41-87 years). Invasive duct carcinoma comprised 95.2% of cases. Tumor grade II and III was seen in 50% and 47.6% of cases, respectively, and advanced stage disease (III/IV) was seen in 45.2% cases (n = 39). Estrogen receptor (ER) was positive in 97.6% cases, progesterone receptor (PR) in 83.3%, androgen receptor (AR) in 76.2%, HER2 in 4.8%, Cyclin-D1 in 92.9%, Bcl2 in 66.7%, GCDFP-15 in 23.8%, p53 in 16.7%, and Ki67 index was low (<14%) in 66.7% cases. Molecular subtyping of these cases revealed 64.3% of luminal A, 35.7% of luminal B, and no HER2 rich/driven category or triple negative case. There was no statistical significance between luminal A and B category pertaining to overall stage of tumor (P = 0.905). Lymph node metastasis was more commonly associated with luminal B category (P = 0.089). p53 positivity showed significant association with luminal A cases (P = 0.002) and nodal metastasis (P = 0.042). GCDFP-15 positivity showed significant association with higher tumor grade (P = 0.042) and stage (P = 0.047). Stage was the most significant prognostic marker (P < 0.0001). On follow-up (n = 27), all the six cases that showed recurrence/persistent disease were high stage (III/IV) on presentation.