Neoadjuvant chemotherapy for triple negative and Her2+ve breast cancer: striving for the standard of care

Abstract

Purpose Neoadjuvant chemotherapy (NAC) for triple negative (TN) and Her2 positive (HER2) breast cancers is supported by international guidelines as it can decrease extent of surgery, provide prognostic information and allow response-driven adjuvant therapies. Our goal was to describe practice patterns for patients with TN and HER2 breast cancer and identify factors associated with the receipt of NAC versus surgery as initial treatment. Methods A retrospective population-based cohort study of adult women diagnosed with stage I-III TN or HER2 breast cancer (2012-2019) in Ontario was completed using linked administrative datasets. The primary outcome was NAC as first treatment. The association between NAC and patient, tumour, and practice-related factors were examined using multivariable logistic regression models. Results Of 12,881 patients included, 22.9% (n = 2952) underwent NAC as first treatment. Patients who underwent NAC were more likely to be younger, have larger tumors, node positive disease and stage 3 disease. Of patients who underwent surgery first, 8.4% were seen by a medical oncologist prior to surgery. On multivariable analysis, increasing tumor size (T2 vs T1/T0: 2.63 (2.13 - 3.25)) and node positive (N1 vs N0: 3.60 (2.88 - 4.50)) disease were both associated increased odds of receiving NAC. Conclusion A considerable proportion of patients with TN and HER2 breast cancer do not receive NAC as first treatment. Of those, most were not assessed by both a surgeon and medical oncologist prior to initiating therapy. This points towards potential gaps in multidisciplinary assessment and disparities in receipt of guideline-concordant care.