New Cardiac Abnormalities Following Radiation Therapy in Breast Cancer Patients Treated With Trastuzumab

Abstract

Materials/Methods: The study cohort included a total of 235 Pts who presented with ILRR from Jan 2005 to Nov 2013. The ITR is defined as the length of time from the date of mastectomy until local and/or regional recurrence occurred. ER, PR, HER2 status, and tumor grade were used to construct the following 5 biologic subtypes: i) luminal A: ER+ or PR+, HER2-, and grade 1 or 2, ii) luminal B: ER+ or PR+, HER2-, and grade 3, iii) luminal HER2: ER+ or PR+, and HER2+, iv) HER2: ERand PRand HER2+, and v) triple negative breast cancer (TNBC): ERand PR-, and HER2-. To account for uncertainties caused by limited numbers of Pts in some subtypes, node-negative Pts were reclassified into two subgroups based on hormone receptor (HR) status, i.e., HR-positive (luminal A, B and luminal HER2) and HR-negative (HER2 and TNBC). The association between subgroup, e.g., constructed biologic subtype, and ITR was evaluated using independent-Samples T test or analysis of variance (ANOVA). Results: The median ITR for the entire cohort was 33.2 (range, 4.5-236) months (Mos.). Overall, biologic subtype specific median ITR were 43.3 (7.9-236.0) Mos. for luminal A (nZ83), 42.2 (6.1-143.3) Mos. for luminal B (nZ58), 23.8 (6.9-47.3) Mos. for luminal HER2 (nZ23), 18.2 (6.6-117.5) Mos. for HER2 (nZ22), and 21.8 (4.5-138.2) Mos. for TNBC (nZ49), and the difference among them was statistically significant (FZ7.9, pZ0.001). For Pts with positive nodes (nZ108), the median ITR was 30.7 (4.9-236.0) Mos., compared to 35.2 (4.5-186.0) Mos. for nodenegative Pts (nZ129) (FZ10.5, pZ0.02). Among node-negative Pts (nZ129), biologic subtype specific median ITR were 56.8 (9.3-186.5) Mos. for luminal A (nZ38), 36.1 (10.5-143.3) Mos. for luminal B (nZ38), 31.8 (10.9-47.3) Mos. for luminal HER2 (nZ14), 15.2 (8.1-117.5) Mos. for HER2 (nZ11), and 21.6 (4.5-138.2) Mos. for TNBC (nZ28), and their difference was statistically significant as well (FZ7.1, pZ0.001). Further, the subgroup of node-negative, HR-positive (nZ90) Pts had a median ITR of 39.1 (9.3-186.5) Mos., which is longer than that in the subgroup of node-negative, HR-negative (nZ39) Pts (21.4 (4.5-138.2) Mos.) (FZ10.2, pZ0.003). Conclusion: Constructed biologic subtype is demonstrated to be associated with interval to recurrence in Pts who developed ILRR after initial treatment with mastectomy and adjuvant systemic therapies but without PMRT. Recurrence may be delayed in Pts with node-negative, HR-positive disease who received adjuvant endocrine therapy. Author Disclosure: R. Jiang: None. J. Ma: None.