Rapid Fire Best of the Best Poster Oral Clinical Oncology Society of Australia Annual Scientific Meeting 2021

The use of neoadjuvant systemic therapy in early breast cancer as a guide to locoregional therapies: A single institution review (#238)

Jessica McKie 1 , Melissa Vereker 2 , Peter Gregory 3 , Joanna Morgan 3 , Steven David 4 , Karen Taylor 5 6 , Michelle White 1 7 , Yoland Antill 1 7
  1. Faculty of Medicine, Nursing and Health Sciences , Monash University, Clayton, Victoria, Australia
  2. Cabrini Institute, Cabrini Health, Malvern, Victoria, Australia
  3. Department of Surgery, Cabrini Health, Malvern, VIC
  4. Department of Radiation Oncology, Peter MacCallum Cancer Centre, Parkville, VIC
  5. GenesisCare, Cabrini Health, Malvern, VIC
  6. Department of Surgery, Monash University, Clayton, VIC
  7. Department of Medical Oncology, Cabrini Health, Malvern, VIC

Aims

Historically used to down-stage locally advanced tumours, neoadjuvant systemic chemotherapy (NSC) creates an opportunity to optimise locoregional therapies. This project aimed to document how NSC affected surgical and radiotherapy decisions in the adjuvant setting.

Methods

Patient data was sourced from the Cabrini Breast Cancer Database from February 2016-September 2020. Decision trees were developed to assess management of the breast and the axilla separately. These were used to determine the proportions that received each treatment in this non-comparative, descriptive analysis. 

Results

A total of 1104 patients were seen for management of early breast cancer. 200 (18.1%) patients received NSC and were therefore eligible for analysis (Her2-/ER-/PR- 53 (26.5%), Her2-/ER+ 75 (37.5%), Her2+/ER- 35 (17.5%), Her2+/ER+ 37 (18.5%)). 80 patients had conservable breast disease prior to NSC and received either breast conserving surgery (BCS) 60 (75%) or mastectomy 20 (25%), followed by adjuvant local radiotherapy 63 (78.8%), or no radiotherapy 14 (17.5%). 120 patients had non-conservable disease prior to NSC. 48 (40%) became conservable after NSC. By disease sub-type Her2-/ER-/PR- 16 (30%), Her2-/ER+ 15 (20%), Her2+/ER- 7 (20%), Her2+/ER+ 10 (27%) patients became conservable after NSC. 72 (60%) remained not conservable. 113 patients were node positive prior to NSC. 57 (50.4%) had a complete nodal pathological response (Her2-/ER-/PR- 12 (23%), Her2-/ER+ 11 (15%), Her2+/ER- 17 (49%), Her2+/ER+ 17 (46%)). 56 (49.6%) remained node positive. 109 (96.4%) patients had an axillary dissection, 87 (77%) received adjuvant radiotherapy. Of the 87 node negative patients, 78 (89.7%) had no further axillary treatment after NSC and sentinel lymph node biopsy.

Conclusions

Increasingly used to guide systemic therapies, NSC frequently results in down-staging of tumour prior to locoregional therapy, potentially permitting breast conserving surgery. Additionally, pathological complete response in the axillary lymph nodes allows for increasingly tailored management of the axilla.