Background: Neoadjuvant chemotherapy (NAC) is the standard of care for locally advanced HER2 + breast cancer (BC). Optimal sequencing of treatment (NAC vs. surgery first) is less clear cut in stage I (T1N0) HER2 + BC, where information from surgical pathology could impact adjuvant treatment decisions. Utilizing the NCDB, we evaluated the trend of NAC use compared to upfront surgery in patients with small HER2 + BC.
Methods: We identified NCDB female patients diagnosed with T1 N0 HER2 + BC from 2010 through 2015. Prevalence ratios (PR) using multivariable robust Poisson regression models were calculated to measure the association between baseline characteristics and the receipt of NAC. Analysis of trends over time was denoted by annual percent change (APC) of NAC versus surgery upfront.
Results: Of the 14,949 that received chemotherapy and anti-HER2 therapy during the study period, overall 1281 (8.6%) received NAC and 13,668 (91.4%) received adjuvant treatment. Patients receiving NAC increased annually from 4.2% in 2010 to 17.3% in 2015, with the most rapid increase occurring between years 2013 (8.5%) and 2014 (14.2%). The greatest increase was seen in patients with cT1c tumors with an APC of 37.8% over the study period (95% CI 29.0, 47.3%, p < 0.01), although a significant trend was likewise seen in patients with cT1a (APC = 26.1%,95% CI 1.59, 56.6%), and cT1b (APC = 27.4%, 95% CI 18.0, 37.7%) tumors. Predictors of neoadjuvant therapy receipt were age younger than 50 (PR = 1.69, 95% CI 1.52, 1.89), Mountain/Pacific area (PR = 1.24, 95% CI 1.05, 1.46), and estrogen receptor negativity (ER- PR + : PR = 2.01, 95% CI 1.51, 2.68; ER- PR- : PR = 1.49, 95% CI 1.32, 1.69).
Conclusions: Neoadjuvant therapy for T1 N0 HER2 + BC increased over the study period and was mostly due increased use in clinical T1c tumors. This may be consistent with secular change in Pertuzumab treatment following FDA approval in 2013.
Keywords: Early-stage breast cancer; HER2-positive; Neoadjuvant chemotherapy.