Abstract P5-16-08: Risk factors of locoregional relapse in locally advanced breast cancer treated with neoadjuvant chemotherapy following mastectomy and radiotherapy

Field: Medicine (Health Sciences)

Abstract Purpose: We seek to investigate the prognostic factors that could possibly affect the local-regional recurrence (LRR) of breast cancer patients who do not achieve pathological complete response (pCR) after neoadjuvant chemotherapy (NCT), and to build a prognostic nomogram to predict patients' outcome. Methods: The retrospective analysis included 510 patients who had received NCT followed by surgery and radiotherapy. The NCT regimens included anthracycline-containing, vinorelbinecontaining, and taxane-containing regimens for a median of 3 cycles. The clinical responses to neoadjuvant chemotherapy were evaluated based on MRI and ultrasound examinations and in accordance with the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. The Miller-Payne (MP) grading system was employed to evaluate the decrease in cancer cellularity. Multivariate analyses were used to identify independent predictors of LRR. Results: The median follow-up for the entire study population was 61 months (range 5-128 months). There were 40 isolated local recurrences, 17 regional-only recurrences and 5 patients with local and regional recurrences. Sixteen patients (25.8%) occurred synchronously with distant metastasis, and no LRR was detected after distant failure. Fifteen patients had recurrences in the supraclavicular field. The 5-year cumulative LRR-free survival rate was 88.0% (95% CI: 85.2%-90.1%). The 5-year overall survival and disease-free survival rates were 79.0% (75.5%-82.6%) and 63.1% (58.9%-67.3%), respectively. Multivariate analysis revealed that positivity for ≥ 4 lymph nodes and Ki-67 index ≥ 14% were independent factors for LRR-free recurrence. The prognostic model was established based on the sum of both independent prognostic factors, with positivity for ≥ 4 lymph nodes and Ki-67 index ≥ 14% individually contributing 1 point to the risk score. The patients in the validation set were assigned to a low-risk group (0 point), median-risk group (1 point) and high-risk group (2 points). The 5-year LRR-free survival rates in the low, intermediate, and high-risk groups were 95.5%, 89.1%, and 67.1%, respectively (p &lt; 0.001). We also show the annual LRR rate among these 3 groups using our single-institution data, as well as to review relevant literature-based data to compare with our observations. Four publications that reported ARR (annual recurrence rate) after surgery for primary breast cancer were identified as eligible. In the relevant literature, the annual risk of local-regional recurrence peaked between two and three years after the initial diagnosis. In contrast, the ARR curve of the high risk subgroup for neoadjuvant patients exhibited one peak near 1 year (17% per annum). The median and low-risk subgroups did not have an obvious recurrence peak. Conclusion: This prognostic model has considerable clinical value in predicting local-regional recurrence, which could help clinicians to design appropriate local-regional treatment specifically and to perform surveillance individually. Citation Format: Chen S, Huang L, Shao Z-M. Risk factors of locoregional relapse in locally advanced breast cancer treated with neoadjuvant chemotherapy following mastectomy and radiotherapy [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 P5-16-08.