Abstract P5-13-04: Needle-to-knife wait time and impact on pCR in patients undergoing neoadjuvant chemotherapy for breast cancer
Authors: Lai V , Hajjaj O , Chia S , Simmons C 
Published: May 2019

Abstract
Introduction: In the setting of pre-operative neoadjuvant chemotherapy (NAC) for the treatment of breast cancer, it is important to ensure coordination between medical and surgical oncology. A study by Sanford et al. show that patients receiving surgery &gt;8 weeks after NAC have worse overall survival. As NAC continues to expand its role in breast cancer treatment, a closer look at the maximal acceptable time between NAC and surgery becomes more important. We wished to assess the impact of time between last dose of chemotherapy and surgery on pathological complete response (pCR), disease free survival (DFS), overall survival (OS), and surgical complications.
Methods: A cohort study was conducted utilizing the BC Cancer Agency's prospective neoadjuvant database, located in Vancouver, BC. Patients were selected if they had undergone NAC with curative intent for treatment of breast cancer, followed by surgical resection. Patients who received neoadjuvant radiation and/or hormone therapy were excluded. Patients were divided into three groups: those who had surgery &lt;4 weeks from last dose of chemo, 4-8 weeks from last dose, and &gt;8 weeks from last dose. Charts were audited for demographic data, tumour characteristics, and complications from surgery. Data was analyzed using a Chi Squared test to determine any differences in pCR, OS, DFS, and surgical complications, between the three different time intervals.
Results: 347 patients were identified and included in this study. The median time to surgery after last dose of chemotherapy was 4.86 weeks (range 0.86-22.86 weeks). The percentage of patients that achieved pCR was 31.3%, 30.5%, and 28.6% in the &lt;4 weeks, 4-8 weeks, and &gt;8 weeks groups respectively (p= NS for all comparisons). There was no difference in pCR observed between the three groups based on receptor status. At the median follow up of 3 years, DFS was 85%, 85.8%, and 85.7% in all three groups. Likewise OS was 95%, 90%, and 89% respectively. The rate of surgical complications are 16%, 23.4%, and 21.4% for the three groups respectively (p=NS).
Conclusions: This study demonstrated no difference between receiving surgery &lt;4 weeks, 4-8 weeks, or &gt;8 weeks after last dose of NAC on pCR, survival, or surgical complications. This finding was preserved in all receptor subtypes. This has important implications for resource allocation. This data may also help in counselling and easing patient anxiety in terms of the urgency (or lack thereof) and wait times for surgery. Subsequent studies with larger sample sizes will help to ensure that clinical differences in outcomes are not affected by wait times.
Comparison of outcome measures based on needle to knife time &lt; 4 weeks (n=80)4-8 weeks (n=239)&gt;8weeks (n=28)p (&lt;4 weeks vs. &lt; 8 weeks)pCR31.3% (25)30.5% (73)28.6% (8)0.791HR+Her2-4.5% (1/22)6.5% (6/92)0% (0/5)--TNBC31.5% (6/19)42.1% (24/57)0% (0/6)--Her2+46.1% (18/39)48.8% (44/90)47.1% (8/17)--3 year DFS85%85.5%85.7%0.9273 year OS95%90%89%0.290Surgical Complication16.3%23.4%21.4%0.536
Citation Format: Lai V, Hajjaj O, Chia S, Simmons C. Needle-to-knife wait time and impact on pCR in patients undergoing neoadjuvant chemotherapy for breast cancer [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 P5-13-04.