e-Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2021

The use of neoadjuvant systemic therapy in early breast cancer as a guide to adjuvant treatment choices: a single institution review (#239)

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

Traditionally reserved to down-stage locally advanced disease, neoadjuvant systemic chemotherapy (NSC) is increasingly common in the management of early breast cancer, allowing in-vivo tumour response to guide adjuvant therapy. This project aimed to document how NSC affected adjuvant therapy decisions.

 

Methods

Patient data was sourced from the Cabrini Breast Cancer Database from February 2016-September 2020. Decision trees were developed based on treatments in 2021 for each pathological sub-type (ER-PR-Her2- or triple negative (TNBC), HER2-negative ER-positive (Her2-/ER+), HER2-positive ER-negative (Her2+/ER-) and HER2-positive ER-positive (Her2+/ER+) disease). These demonstrated the proportions who received each treatment in this non-comparative, descriptive analysis.

 

Results

A total of 1104 patients were seen for early breast cancer therapy with 200 (18.1%) having received NSC and therefore eligible for analysis (TNBC 53 (26.5%), Her2-/ER+ 75 (37.5%), Her2+/ER- 35 (17.5%), Her2+/ER+ 37 (18.5%). 66 (33%) patients achieved a pathological complete response (pCR) to NSC (TNBC 25 (47.2%), Her2-/ER+ 6 (8%), Her2+/ER- 21 (60%), Her2+/ER+ 14 (37.8%)) and had no further systemic treatment or standard adjuvant therapies. Of patients with residual disease (TNBC 28 (52.8%), Her2-/ER+ 69 (92%), Her2+/ER- 14 (40%), Her2+/ER+ 23 (62.2%)), 30 (15%) had a change from standard or additional therapiesncluding 10 (5%) who were referred to clinical trials and 1 (1.3%) Her2-/ER+ patient who received adjuvant chemotherapy and endocrine therapy with weak estrogen expression in the residual disease. 5 (2.5%) patients had tumour progression and changed their NSC 3 (1.5%) or ceased early 2 (1%) before all proceeded to surgery.

 

Conclusion

NSC allows for response assessment and subsequent therapy adjustment aimed at reducing risks of recurrence and increasing overall survival. This was particularly seen in patients with TNBC or Her2+ tumours with residual disease. Moving forward, more patients are likely to benefit from informed adjustment of adjuvant therapies, with available or emerging agents, following NSC.