Loss of HER2-positivity following neoadjuvant targeted therapy for breast cancer is not associated with inferior oncologic outcomes.

BACKGROUND: Patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer are treated with trastuzumab-based neoadjuvant therapy (NAT); some patients with residual disease post-NAT show loss of HER2 amplification and has been inconsistently associated with oncologic outcomes. METHODS: We queried our multi-institutional cancer registry for women with HER2-positive breast cancer undergoing NAT from 2011 to 2018. Clinicopathologic, treatment-related, and outcomes data were collected. Kaplan-Meier and Cox proportional hazards analysis were used to evaluate oncologic outcomes. RESULTS: A total of 348 patients were identified; 166 (48%) had a pathologic complete response. Of the 182 patients with residual disease, 87 (48%) were HER2-positive, 34 (19%) were HER2-negative, and 61 (33%) were HER2-unknown, with a median follow-up of 44 months. There were no factors associated with HER2 loss apart from age. On Kaplan-Meier analysis, estimated 5-year recurrence-free survival (RFS) and overall survival (OS) for patients with HER2-positive residual disease was 81% and 92%, respectively, and 74% (log rank p = 0.75) and 81% (p = 0.35) in patients with HER2-negative residual disease. CONCLUSION: The loss of HER2-positivity following NAT is not associated with worse 5-year RFS or OS. We do not recommend retesting HER2 status following NAT for the purpose of clinical management; these patients should complete targeted adjuvant therapy.

Variation in adoption of skin and nipple sparing mastectomy: An opportunity to enhance patient outcomes.

BACKGROUND: Nipple-sparing mastectomies (NSM) for breast cancer are under-utilized. We sought to investigate NSM utilization. METHODS: Females with nonmetastatic breast cancer undergoing mastectomy in the Legacy Health System from 2007 to 2020 were identified. Multivariable logistic regression was utilized to evaluate odds of receiving NSM. RESULTS: Three-thousand-four-hundred-seventeen mastectomies were performed with 772 undergoing NSM. On multivariable analysis, later year (OR 1.22/year, P < 0.001), neoadjuvant chemotherapy (OR 1.33, P = 0.04), HR+ (OR 1.61, P = 0.001) and surgeon volume (OR 1.16/10 yearly mastectomies, P < 0.001) were independently associated with increased odds of receiving a NSM while age (OR 0.94/year, P < 0.001), IDC (OR 0.58, P = 0.01), T3/T4 stage (OR 0.36, P = 0.009), and clinical node positivity (OR 0.63, P = 0.003) were independently associated with decreased odds. Surgeon volume was not associated with odds of receiving a non-NSM with reconstruction (OR 1.01 P = 0.48). CONCLUSION: NSM is under-utilized by low-volume breast surgeons. Understanding barriers to adoption is an is an opportunity to enhance patient-centered outcomes.