Abstract P1-08-33: Molecular breast cancer subtypes in a Guatemalan population. Classification according to immunohistochemical markers: Clinicopathologic feature and survival analysis

Introduction: Breast cancer is a heterogeneous malignancy and it9s possible to identify by simple techniques, such as inmmunohistochemistry, four subtypes with different clinical and biological behavior. Our aim was to evaluate the influence of these subtypes on the local and distant recurrences rates. Method: data of 954 unilateral breast cancer patients primarily treated with radical or conservative surgery from 2008 to 2014 were obtained from medical records. Breast cancer subtypes were categorized in Luminal A (RE+ and/or RP+, HER2-), Luminal B (RE+ and/or RP+, HER2+ o Ki-67> 14%); HER2 (RE-, RP-, HER2+) and triple negative tumors (TNT) (RE-, RP-, HER2-). Patterns of recurrence for each subtype and clinicopathological variables and the influence of each variable on the overall survival (OS) by the Kaplan-Meier method. In all cases, we determined histological type, grade nuclear (low, intermediate vrs high), tumor size, lymph node involvement Results: Median age at diagnosis was 52 years (range, 23-95). Of these patients 55% were premenopausal. We found that 522 (56%) of the cases were luminal A breast cancer, 190 (20%) of the cases were triple negative tumors (TNT), luminal B were 73 (8%) and it was HER2-positive in 152 (20%) of cases. Nine patients (3%) had other breast cancer contralateral. In 70% of all the cases were found in locally advanced stages (IIB – IIIC). In 438 (70%) of all the cases were found in locally advanced stages (IIB – IIIC), 773 (81%) patients underwent radical mastectomy and 181 (19%) undergoing conservative surgery. We performed univariate analysis to evaluate recurrence-related factors. Variables included in the analysis clinical stage (I – IIa vs IIb – IIIC; 88% vs 70%; p = 0.001, ), nuclear grade (grade 1, 2 vs 3; 83% vs 62%; p = 0.01) and pathologic response (total vs parcial, stable disease; 76% vs 54%; p = 0.01), and status Her-2 subtype so borderline (positive vs negative; p= 0.079). A univariate survival analysis stratification according to clinicapathologic characteristics. Clinical stage, histologic grade, response to neoadjuvant and tumor size were identified as significant factors of prognosis for the OS. (p=0.5) and histological subtypes Luminal A (94%), Luminal B (75%), HER2 (79%) and TNT (68%), p= 0.001. Conclusion: this study demonstrates that treatment efficacy is similar to that reported in the literature and emphasizes the need for establishing the molecular breast cancer subtypes and efforts should be made to reduce the high frequency of advanced-stage diagnoses. Citation Format: Castro H, Garcia L, Jimenez F, Ramos P, Castro N. Molecular breast cancer subtypes in a Guatemalan population. Classification according to immunohistochemical markers: Clinicopathologic feature and survival analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-08-33.