Abstract P3-03-14: Clinical utility of one-step nucleic acid amplification (OSNA) in axillary surgery after neoadjuvant chemotherapy (NAC)

Introduction

NAC has been used for downsizing of the tumour in breast and axilla to allow more conservative surgery. In the NAC setting, intraoperative assessment of sentinel lymph node(s) (SLN) is still considered necessary1. Current awareness of the prognostic value for axillary nodal down-staging has renewed interest in analysis of SLN post-NAC.

In this study we want to examine the clinical utility of OSNA (based on CK19 mRNA detection) as a method of intra-operative analysis of SLN to assist real-time decision-making for axillary surgery post-NAC in early breast cancer (EBC).

Methods

Retrospective analysis of prospective data on 399 consecutive patients with EBC who received NAC followed by breast surgery with SLN biopsy (408 axillae) and assessment by OSNA, from September 2011 to January 2018 at the Royal Marsden Hospital (UK). OSNA readouts from the Sysmex RD-100i were collected separate to and blinded from clinico-pathological data. A negative or benign pre-treatment axillary ultrasound scan or indeterminate ultrasound with negative or benign axillary cytology/histology prior to NAC was considered cN0. Univariate analysis (significance at p<0.05) was used to identify risk of recurrence. Patients had a median (mean) follow up of 32.5 (36) months.

Results

The median age at diagnosis was 49 years, median BMI 26, 41 EBC (10%) were screen-detected, 292 (72%) were grade 3 and the most frequent phenotype was receptor triple negative (n=132, 32%).

Of 408 axillae, 248 (60%) were initially cN0, of which 113 (46%) had a pathological complete response (pCR) in the breast. SLN in 54 (22%) cN0 patients were positive on OSNA, of which only 6 (9%) had further involved axillary nodes all 6 of which were ER+ Her2-.

The remaining 160 (40%) axillae were cN1 of which 87 (54%) had conversion to ypN0 including 55 (34%) with both ypT0ypN0.

Axillary lymphadenectomy (AL) was performed in 79 (19%) patients overall, of which n=22 (28%) were cN0 and 57 (72%) were cN1. Of these, 30 (53%) of the cN1 and 6 of 22 (45%) of cN0 had at least 1 additional positive AL node.

Overall 59 (14.4%) patients relapsed. A significantly worse rate of relapse was observed in cN1 compared to cN0 patients (37/159 (23.3%) versus 22/244 (9%), p<0.001). Combined pCR of both breast and axilla (in cN1, n=54) was associated with a significantly reduced risk of relapse and death (p<0.001) compared to those without pCR of either breast or axilla (n=62). Of the latter 18 (29%) relapsed (including 10 deaths).

The mean of both the single highest node tumour load (and total nodal tumour load), as measured by CK19mRNA copies/ul on OSNA, were significantly higher at 90,000 (98,300) for those who relapsed versus 23,100 (25,100) for those without relapse (p=0.027).

Conclusions

The OSNA assay is an accurate tool for axillary SLN analysis in patients after NAC and was helpful in intra-operative axillary management. OSNA reduces the need for a second surgery for AL in 20% of breast cancer patients with a positive-SLN after NAC and might offer additional prognostic value.

Reference

1. NCCN. National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology Breast Cancer.2016.Version 2.2016.

Citation Format: Muscara F, Christaki G, Richardson C, O'Connell R, Padmanabhan P, Warwick J, Lee Y, Smith I, Nerurkar A, Osin P, Krupa K, Rusby J, Roche N, Gui G, MacNeil F, Barry P. Clinical utility of one-step nucleic acid amplification (OSNA) in axillary surgery after neoadjuvant chemotherapy (NAC) [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 P3-03-14.

Does Having Primary Breast Reconstruction Influence Chest-Wall Radiotherapy Rates?

BACKGROUND: Immediate breast reconstuction should be discussed with all patient's who require mastectomy. The immediate recontruction may interfere with postmactectomy chest wall radiotherapy (RT) .The adverse impact of chest-wall radiotherapy on the reconstructed breast is widely reported. Predicting who will require chest-wall RT prior to surgery can be difficult, limited to the knowledge of full pathological staging and often only known after mastectomy. Does having primary reconstruction influence in chest-wall RT decision making? Are women who opt for primary reconstruction less likely to receive RT than those who choose no reconstruction?METHODS: From 1st Jan 2008 to 31st March 2009, we performed 430 mastectomies 226 were mastectomy only (M0), 204 were mastectomy with immediate reconstruction (MIR). Data were prospectively recorded on chest wall recurrence risk adjuvant chest wall radiotherapy, type of breast reconstruction (tissue expander, fixed volume implant, autologous reconstruction only and autologous reconstruction implant assisted).Chest-wall recurrence risk was calculated from pathology.RESULTS:Performed 430 mastectomies, 335 for invasive disease, 53 for DCIS, 6 for ALH/LCIS, 36 benign (for risk reduction or symmetry purposes).Two hundred and twenty-six (52%) were mastectomy only (M0), 204 (48%) were mastectomy with immediate reconstruction (MIR).Chest wall radiotherapy + MO vs. MIRTotal RT 130(30%), of which 88 (67%, 88/130) and 44 (33%, 44/130) were MO and MIR respectively. MOMO+RTMIRMIR+RTLow Risk (ASCO pN-ve/T<50mm)42 (18%,42/226)4 (9%,4/42)44 (21%,44/204)2 (4%,2/44)Moderate Risk (SUPREMO pN+ (1-3) and/or pT2)89 (39%)31 (34%,31/89)59 (29%)23 (39%,23/59)High Risk (ASCO pT_>50mm and/or pN+_> 4)77 (32%)53 (73%,53/77)29 (14%)19(65%,19/29) RT and Type of Reconstruction: Of the 204 MIR, 85 (42%) were autologous and 119 (58%) implant based of which 16 autologous (18%,16/85) and 30 (25%,30/119 ) implants received RT.CONCLUSION:Chest wall RT rates are broadly comparable across the three risk groups for MIR and MO suggesting MIR doesn't influence decision making regarding RT.The number of high risk MIR was small (14%) suggesting successful preoperative selection.Slightly higher radiotherapy rate for implant based reconstruction may be explained by staged reconstruction.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3119.