The standard of care has been transformed with innovative treatment options for patients with human epidermal growth factor receptor 2 (HER2)-positive early breast cancer and the treatment landscape continues to evolve. Preet K. Dhillon and colleagues presented a study with the primary objectives of comparing the demographic and clinical characteristics of patients with HER2-positive early breast cancer who received neoadjuvant or adjuvant treatment, describing the common neoadjuvant or adjuvant regimens according to hormone receptor (HR) status, and finally to characterize trends in neoadjuvant treatment use.
Data from an electronic health record database between 2011 and 2020 of more than 2.4 million patients with cancer from more than 280 clinics largely from community-based practices were obtained.
Included in the study were patients with HER2-positive early breast cancer treated with systemic or oral antineoplastic treatments either prior to (neoadjuvant) or within 6 months (adjuvant) of the first primary surgery date. Adjuvant treatment also required at least 6 months of follow-up and was captured for up to 1 year after initiating adjuvant treatment.
In the neoadjuvant setting, patients with HER2-positive breast cancer compared with those in the adjuvant setting alone, were more likely to have been treated at an academic center, premenopausal, younger, diagnosed with clinical stage II or III disease, or with HR-negative disease; these patients were more than twice as likely to have bilateral mastectomies. Conversely, what did not carry an association based on neoadjuvant versus adjuvant treatment status, were histology, laterality, tumor grade, and race and ethnicity.
Fewer than 20% of patients diagnosed with HER2-positive early breast cancer initiated neoadjuvant treatment; however, this increased to approximately 50% over a 6-year period. A total of 78% of patients receiving neoadjuvant therapy were treated with a dual blockade of HER2 with trastuzumab plus pertuzumab and a taxane-based chemotherapy regimen. Eleven percent of neoadjuvant patients received an anthracycline-based regimen plus HER2-targeted therapy. Expectedly, most patients were administered HER2-targeted therapy alone with trastuzumab and pertuzumab postsurgery.
For adjuvant-only patients, the most common form of chemotherapy included a taxane-based regimen in combination with HER2-positive dual blockade therapy, trastuzumab with or without pertuzumab.
In the postsurgery setting, hormonal therapy was the most frequently administered treatment (adjuvant continuation, 61%; adjuvant only, 78%); however, in the neoadjuvant setting, it was less commonly used (9%).
Patients with HR-positive early breast cancer were more commonly treated with “other” therapy and hormonal therapy; adjuvant-only patients with HR-negative disease were more commonly administered HER2-targeted therapies with taxanes (83% vs 54%), regardless of the additional use of platinum-based chemotherapy (64% vs 38%) or anthracyclines (15% vs 8%).
Patterns were revealed through analysis of the data; there has been an increase in neoadjuvant therapy use, which is in line with shifts in the standard anti-HER2 therapies that have arisen since 2013. Regardless of significant changes, neoadjuvant patients are primarily treated with dual HER2 blockade and chemotherapy, with a taxane-based regimen preference.
Source: Dhillon PK, Flores C, Sanglier T, et al. Neoadjuvant (neoadj) and adjuvant (adj) treatment patterns in HER2-positive early breast cancer (EBC): analysis of US real-world oncology data. Presented at: 2020 San Antonio Breast Cancer Symposium, December 8-11, 2020. Abstract PS10-20.