Abstract P5-08-36: Contemporary risk of local breast cancer recurrence after neo-adjuvant chemotherapy: Results of a population-based cohort study

Abstract

Abstract Introduction Neo-adjuvant chemotherapy (NAC) is increasingly used in breast cancer to enable less extensive surgery and monitor the response to systemic therapy. Little is known about local recurrence (LR) in patients who received NAC. However, this information is important when deciding on optimal local treatment in these patients, especially since NAC is increasingly being offered to patients with smaller tumors. The aim of this study is to assess the contemporary rates of local breast cancer recurrence in patients that received NAC. Methods All women treated with NAC for primary invasive breast cancer in the years 2003-2008 were selected from the Netherlands Cancer Registry. The first event within five years after NAC was included for analyses. The 5-year local (LR) recurrence rate was calculated using Kaplan Meier estimates and the prognostic value of various clinicopathological and treatment factors was evaluated. Results A total of 2,457 patients were identified of whom 43% had cT1-2, 25% cT3 and 29% cT4 tumors. Two-thirds of the patients had metastatic lymph node involvement and 85% received adjuvant radiotherapy. The overall 5-year risk of LR was 6.7% and decreased from 2003-2008. Table 1. Overall 5-year rate of local breast cancer recurrence in 2,457 breast cancer patients that received neo-adjuvant chemotherapy in the period 2003-2008. Local recurrencea NRate2003N=412309.6%2004N=429288.0%2005N=549398.1%2006N=604234.7%2007N=406164.7%2008N=489245.5%TotalN=2,4571606.7%aLocal recurrence defined as ipsilateral in-breast recurrence or new primary Rates represent Kaplan Meier estimates The LR-rate was lower in hormone receptor positive (HR+) than HR-negative (HR-) tumors (3.3% vs. 12.9%) and increased with larger residual tumor size (from 1.2% in ypT0 to 13.0% in ypT3 and 16.1% in ypT4 tumors). The LR-rate also increased with the ypN-stage (4.1% in ypN0, 5.7% in ypN1 and 11.3% in ypN>1 patients) and was lower following breast-conserving surgery (BCS) than after mastectomy (4.8% vs. 7.2%). Currently, we are working on the multivariate analyses, which will be available at the San Antonio Breast Cancer Symposium. Conclusions The rate of LR in patients treated with NAC has decreased over time. This will most likely be caused by enhanced imaging and radiotherapy techniques, as well as by increased insight in tumor biology resulting in improvements in both the development and application of systemic treatment modalities. Multivariate analyses will have to provide further insight into the risk of developing LR in patients treated with NAC, as well as into the prognostic value of different clinicopathological factors. Citation Format: Aalders KC, Sonke GS, van der Heiden-van der Loo M, Boersma LJ, van Diest PJ, Siesling S, van Dalen T. Contemporary risk of local breast cancer recurrence after neo-adjuvant chemotherapy: Results of a population-based cohort study. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-08-36.