Abstract 206P
Background
Triple negative breast cancer (TNBC) is a very heterogenous and poorly understood disease. This study analyses characteristics and outcomes of TNBC with special histological types.
Methods
We evaluated a cohort of patients (pts) with TNBC and special histological types treated from 2009 to 2020 at a large cancer center. Differences in clinical characteristics were analyzed with one-way ANOVA and Chi-square tests; Kaplan-Meier and Cox regression were used for survival analyses.
Results
141 pts with TNBC special histological types were identified: 75 metaplastic (Met), 16 medullary (Med), 13 lobular (Lo), 13 adenoid cystic (AC), 10 apocrine (Ap), and 14 other types. Younger median ages were observed in Met (51y) and AC (52y) carcinomas, while older median ages occurred in Ap carcinomas (66y) (P=0.004). Stage III-IV disease at diagnosis occurred in 61% of Lo and 52% of Met carcinomas. Med and AC carcinomas had earlier stages (62% and 83% with stage I-II) (P=0.035). Lo, Met, and Med tumors were mostly grade 3 (69-93%), and Ap and AC tumors had lower grade (70-85% grade 1-2; P<0.001). With a median follow-up of 50 mo, 5-y overall survival rates were 47% for Lo, 56% for Met, 86% for Med, 85% for Ap, and 82% for AC carcinomas. Among 125 pts with localized disease, 55 and 48 received neo and adjuvant chemotherapy (CT), respectively. Complete response (CR) rates after neoadjuvant CT were higher in Med carcinomas (100%, n=7/7); while 33% Lo (n=2/6), 12% Met (n=4/32), none Ap (n=0/2), and none AC (n=0/4) carcinomas had CR (P<0.001). No patient with Ap tumor had a disease recurrence; recurrence ranged from 12-33% in other histological subtypes. 5-y disease-free survival rates were 100% for Ap, 87% for Med, 70% for AC and 60% for Lo and Met tumors. 48 pts had metastatic disease; most used first-line regimens were platinum-doublets (39%) and taxanes (16%). Among Met tumors, median progression-free survival was 25 mo with platinum vs 15 mo with other regimens (HR 0.50; P=0.162).
Conclusions
Our data confirm that TNBC have diverse behavior, response to CT, and survival according to histological type. A better comprehension of special types’ byology and molecular features is urgently needed for the development of personalized therapy.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
R.R.D.C.C. Bonadio: Financial Interests, Personal, Expert Testimony: Aché; Financial Interests, Personal, Funding, financial support for attending symposia: Roche; Financial Interests, Personal, Invited Speaker, financial support for educational program: AstraZeneca. All other authors have declared no conflicts of interest.