Surgical outcomes following neoadjuvant chemotherapy
Published Date: 01st May 2020
Publication Authors: Whitehead IJ
Introduction
Potential advantages of neoadjuvant systemic therapy (NST) include downstaging disease to minimise surgery, and in vivo assessment of tumour sensitivity to therapeutic drugs. Considerable variation in NST use remains, however, and it is unclear whether pathological response rates reflect those reported in trials, or whether the downstaging achieved with neoadjuvant treatment impacts on surgical decision-making.
Aims/objectives
The NeST prospective multicentre study aimed to examinesurgical decision making and outcomes following the use of neoadjuvant systemic therapy in early breast cancer across UK breast cancer units.
Method(s)
Women undergoing NST as their primary breast cancer treatment (chemotherapy (CT), endocrine (ET) and targeted therapies) in 37 UK centres from 1/12/17 to 30/11/18 were included. Patient characteristics, tumour pathology, stage systemic treatments, surgical management data and pathological outcomes were collected.
Result(s)
926 patients received neoadjuvant chemotherapy (NAC) for 941 tumours (15 bilateral) during the study period. 46% had HER2+ disease, 32% triple negative disease and 21% ER+ HER2- disease. 51% (474 tumours) were node positive and 48% (456 tumours) node negative (1% unknown nodal status) at diagnosis. Cited indications for NAC were as follows (more than one option applicable to each patient): Downstaging (mastectomy to breast conservation) 37% Facilitate dual antiHER2 therapy 33% Inoperable disease 19% Improved cosmesis (reduced volume of excision) 17% Facilitate BRCA testing 9% Inflammatory breast cancer 6% Centres were asked to indicate primary breast surgical treatment recommended prior to/without NST. At abstract submission, this data was available for 887 patients. 31 had inoperable disease. A total of 477 were considered to require mastectomy, with disease not amenable to breast conservation surgery (BCS). A further 379 patients were considered candidates for BCS. Data on final surgical procedure was available for 765 patients. Of those patients determined suitable only for mastectomy at diagnosis, 123 underwent BCS as their primary operation: a downstaging rate of 26%. The overall mastectomy rate in this cohort was 48%, with 33% having mastectomy and 15% mastectomy with immediate reconstruction. In patients who were node negative at diagnosis, the axillary management plan was for sentinel lymph node biopsy (SLNB) after treatment in 372 cases (82%), with pre-treatment SLNB proposed in 45 cases (10%). In patients who were node positive pre-treatment, the planned axillary surgery was an axillary dissection in 308 patients (65%), with MDTs stating a plan to re-assess the axilla following treatment in only 153 cases (32%). Pathological response data was available in 672 patients, with an overall pathological complete response (pCR) rate of 29% (defined as no residual invasive or in situ disease). pCR rate according to molecular subtype was 37% for HER2+ disease, 35% for TNBC and 7% for ER+, HER2-ve disease. The pCR rate in patients downstaged from mastectomy to BCS was 27%.
Conclusion(s)
This UK national prospective study suggests that surgical downstaging remains a key indication for the use of NAC. Following NAC, 26% of patients in this series were downstaged from an original surgical plan for mastectomy, with NAC enabling BCS in these patients, confirming that this is a successful strategy for increasing breast conservation rates. However, based on this data it appears that surgical downstaging is no more likely in those with pCR compared to those without a pCR. In the UK, the majority of patients who are node negative at diagnosis undergo post-treatment SLNB. However, most patients who are node positive pre-treatment are recommended to undergo axillary node clearance following chemotherapy, with only one third of cases having axillary re-assessment. Data collection is ongoing; updated data will be presented in January 2020.
McIntosh, SA; Whitehead, IJ et al. (180). Surgical outcomes following neoadjuvant chemotherapy: A UK national prospective multi-centre cohort study. Breast Cancer Research and Treatment. 2020 (Supp 2), 528-529