Not all small HER2 positive breast cancers have the same clinical outcome in the North-East of Scotland

Abstract

HER2-positive breast cancers, representing up to 20% of all breast cancers, are more aggressive and have poorer outcomes. Systemic therapy has been proven to prevent disease recurrence and improve survival. Existing literature provides only limited evidence to support this in smaller HER2-positive tumors. The study aimed to evaluate HER-2 positive breast cancer management and treatment of all T1N0 tumors in the North of Scotland, diagnosed 2012–2019. Clinical-pathological details, comorbidities, treatments and clinical events were retrieved from the Scottish North Cancer Alliance audit database and analyzed using univariate and multivariate analysis including cox-regression and log-rank testing (SPSSv23).Overall, 299 patients (41% screen detected/ 56.9% symptomatic /2.1% other), median age 63 years and median tumor size 13 mm, were included. Most cancers were grade 2/3 (43.1%/ 55.5%). Most patients (59.5%) received treatment with trastuzumab (tT); 40.8% concurrent with chemotherapy and endocrine therapy. 7.7% of patients received neo adjuvant chemotherapy. Median follow-up time was 2.6 years, with recurrence on average occurring 2.9 years after diagnosis. Patients receiving trastuzumab were younger, had a higher grade and larger size tumor. 78.5% of patients in the untreated group (non-tT) were ER positive compared to 65.2% in the treated group (tT). Trastuzumab significantly lowered breast cancer recurrence (Tt=3.4% versus non-Tt=8.3%, p = 0.022 HR= 0.096, 95% CI 0.025–0.361). In conclusion, receiving anti-HER2 treatment significantly improved clinical outcome in this T1N0 patient group. Consideration, at the very least informed discussions with patients, should be undertaken to treat these early stage HER2-positive breast cancers.

Keywords

• Breast cancer
• HER2 positivity
• Recurrence
• Systemic therapy