Abstract P1-09-12: TP53 expression in relation to clinical and etiologic factors in breast cancer subtypes

TP53 is a well-known tumor suppressor gene and mutations in TP53 are the most frequent genomic event in most cancers including breast cancer. Recent studies have shown that the frequency, spectrum, timing, and clinical implications of TP53 mutations varied in different molecular subtypes of breast cancer. For example, the frequency of TP53 mutations is the highest in basal-like subtype and lowest in luminal A tumors. However, the evaluation of TP53 protein expression, as a surrogate for TP53 mutations, in large studies in the context of tumor subtypes is limited. In addition, the etiologic relevance of TP53 expression is yet to be investigated. The goal of this study is to evaluate the association of clinical and breast cancer risk factors with TP53 expression, measured using immunohistochemistry (IHC), in breast cancer molecular subtypes. The analysis included 7,226 women with invasive breast cancer who were diagnosed and treated in a tertiary hospital in Beijing, China. Subtypes were defined as Luminal A: ER+ and PR+, HER2–, and low grade (grades 1 or 2); luminal B/HER2–: ER+ and/or PR+, HER2–, and high grade (grade 3); luminal B/HER2+: ER+ and/or PR+, HER2+ (regardless of grade); HER2-enriched: ER–, PR–, and HER2+; Triple-negative (TN): ER–, PR–, and HER2–. As expected, positive TP53 staining showed the lowest frequency in the luminal A (46%) and highest in the TN (61%) and HER2-enriched (63%) subtypes (P-value Citation Format: Yang XR, Abubakar M, Guo C, Koka H, Sung H, Guida J, Deng J, Zhou B, Hu N, Lu N. TP53 expression in relation to clinical and etiologic factors in breast cancer subtypes [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 P1-09-12.