High Ki-67 expression is a marker of poor survival in apocrine breast carcinoma

Apocrine carcinoma is a very rare type of breast cancer, which represents 0.5-4% of all breast cancers. The aim of the study was to analyze biological and clinical features of apocrine carcinoma and their influence on patients survival. The studied group consists of 57 patients, who underwent treatment between 1987 and 2010. Expression of ER, PgR, HER2, AR, GCDFP-15, EGFR, CK 5/6, CK 8/18 and Ki-67 was assessed immunohistochemically on formalin-fixed paraffin-embedded tissue sections. Presence of emboli and extent of lymphocyte infiltration were assessed on haematoxylin-eosin-stained slides. In the investigated group, 16 cases were ER/PgR positive and 49 were AR-positive. ER/PgR-negative tumours were often characterised by CK5/6 and EGFR positivity. The presence of AR was related to HER-2 and GCDFP-15 expression and tumours with expression of CK5/6 were more likely be EGFR positive and had higher Ki-67 LI. Higher probability of 10-years OS and DFS was observed in patients with tumours characterized by Ki-67 LI < 20% (p = 0.036 and p = 0.009, respectively). Favourable trend in OS was noted for patients with smaller tumours (p = 0.053), without lymph node metastases (p = 0.074) and without EGFR expression (p = 0.060). In apocrine breast carcinoma expression of Ki-67 is one of the most important factors influencing patients' survival.