The association between biological subtype and locoregional recurrence in newly diagnosed breast cancer

We investigated the association between the risk of locoregional recurrence (LRR) and biological subtypes defined by hormonal receptors (HR) and HER-2 status in women with invasive breast cancer (BC). A total of 618 newly diagnosed BC patients were identified from a cancer registry within a single institution with standardized methods of tumor assessment for estrogen receptor (ER), progesterone receptor (PR), and HER-2. Patients were stratified based on surgical treatment, breast-conserving therapy (BCT) versus modified radical mastectomy (MRM), as well as biological subtypes: HR+/HER-2- (ER-positive or PR-positive, HER-2-negative), HR+/HER-2+ (ER-positive or PR-positive, HER-2-positive), HR-/HER-2+ (ER-negative and PR-negative, HER-2-positive) and TN (ER-negative, PR-negative and HER-2-negative). The association between clinicopathological factors, biological subtype and LRR was evaluated with univariate and multivariate Cox analysis. With a median follow-up of 4.8 years, the rate of LRR was 7.5%. On multivariate analysis, TN, tumor size ≥2 cm and lymph node (LN) positivity were associated with increased risk of LRR (P = 0.023, P = 0.048, and P = 0.0034, respectively). In BCT group, HR-/HER-2+ and LN positivity were associated with increased risk of LRR (HR 11.13; 95% CI 2.78-44.53; P = 0.0007 and HR 5.40; 95% CI 1.67-17.43; P = 0.0048, respectively). In MRM group, TN subtype and LN positivity were associated with increased risk of LRR (HR 4.72; 95% CI 1.53-14.52; P = 0.0069 and HR 3.23; 95% CI 1.44-7.29; P = 0.0047, respectively). Compared to HR+/HER-2-, HR-/HER-2+ treated by BCT and TN treated by MRM showed a significant decrease of 5-year LRR free survival (P = 0.0002 and P = 0.002, respectively). Tumor profiling using ER, PR, and HER-2 biomarkers is a promising tool to identify patients at high risk of LRR based on surgical treatment. Our findings suggest a different follow-up and locoregional treatment for patients with HR-/HER-2+ and TN subtypes.