Abstract P5-16-20: Impact of “immunohistochemistry-based molecular subtype” on chemo-sensitivity and survival in Hispanic breast cancer patients following neoadjuvant chemotherapy (NAC)
Authors: Gomez-Wolff R , Garcia H , Ossa C 
Published: March 2017

NAC it´s the standard procedure when handling non-surgical tumors and inflammatory breast carcinomas, increases the possibility of conservative surgery and must be considered an evaluative tool in designing a therapeutic strategy. NAC improves Disease-Free Survival (DFS) and Overall Survival (OS) in patients achieving pathological complete response (pCR). “Immunohistochemitry-Based Molecular Subtyping” (IMS) with ER, PR,HER2 and KI67 has shown good correlation with gene expression assays to identify Intrinsic Molecular Subtypes. The relationship between IMS, chemo sensitivity and survival is currently a matter of interest. Achieving pCR at the time of Surgery has been associated with a favorable prognosis.

Objectives:to investigate the pathological response to NAC and its correlation with IMS, as well as its correlation with DFS and OS in patients who have undergone NAC.

Methods: Women &gt; 18 years old. treated with NAC and surgery at IDC (January 2009 to December 2013).Demographic, clinical en follow-up variables were obtained from de IDC patient´s registry. Patient´s vital status was traced trough phone calls.pCR was defined as ypT0 ypN0 (the absence of invasive cancer AND in situ cancer in the breast and axillary nodes). IDC´s IRB approved the research project.

Results: A total of 592 patients fulfilled the study's inclusion criteria. The distribution by subtypes were: “Luminal A”: 150 (25.3%), “Luminal B/HER2 -”: 189 (31.9%), “Luminal B/HER2+”: 114 (19.3%), “HER2-enriched”: 45 (7.6%) and “Triple negative”: 94 (15.9%). The median follow-up was 51 months (interquartile range: 37-68).Pathological response to NAC was: complete pathological response (pCR) in 59 (10%) patients, partial pathological response in 426 (72.0%); stable disease in 82 (13.8%), and progression in 25 (4.2%) patients.In Multivariable Cox Regression Models, pCR is associated with a significant improvement in the DFS (HR 6.89; 95% CI: 2.53 to 18.75. p=0.01) and OS (HR 6.82; 95% CI 2.13 to 21.78. p=0.01). By “Immunohistochemistry-based molecular subtype” the pCR is associated with a significantly better DFS for “Luminal B”, “Triple Negative” and “HER2-enriched”. For OS we found significantly association with pCR for “Triple negative” and “”Luminal B” “Immunohistochemistry-based molecular subtype”. The “HER2-enriched”shown a trend to better OS if obtain pCR (p=0.05).

Conclusions: pCR is associated with an improved overall survival and disease-free survival rates in this group of Hispanics patients. In advanced stages, histologial grade 3, Luminal B, Triple Negative and HER2+ enriched tumors the pCR is associated with a significantly better DFS .

Citation Format: Gomez-Wolff R, Garcia H, Ossa C. Impact of “immunohistochemistry-based molecular subtype” on chemo-sensitivity and survival in Hispanic breast cancer patients following neoadjuvant chemotherapy (NAC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-20.