Optimal time for adjuvant therapy initiation in breast cancer patients: A single center experience

Abstract

Introduction. This retrospective study evaluates the association between the time of chemotherapy initiation and disease free survival in regard to breast cancer subtypes and stage at diagnosis. Material and Methods. The study included a total of 1075 breast cancer patients, stages I - III, treated at Oncology Institute of Vojvodina, Serbia (from 2010 to 2012; n = 617). The gathered data included prognostic factors used in everyday practice. Patients were divided into three groups according to the interval between surgery and chemotherapy (? 30, 31 - 60, ? 61 days). Disease free survival was calculated. Results. Among the 617 patients, the 5-year disease free survival estimate was similar: 81.5%, 81.0%, 84.6% (log-rank test, p = 0.728) regarding the time of adjuvant chemotherapy initiation: ? 30 days, 31 - 60, and ? 61 days, respectively. The study showed that 85% of our breast cancer patients started adjuvant chemotherapy within 3 months after definitive surgery. In multivariate analysis, independent prognostic factors for disease free survival were nodal status and tumor size. The 5-year disease free survival estimate was 85.8% (p = 0.001) for patients with luminal- A subtype (Estrogen +, Progesterone high, human epidermal growth factor receptor 2-, Ki-67 < 20%) with a median follow-up of 62,7 months; for patients with luminal-B (Luminal B (human epidermal growth factor receptor 2 -) Estrogen +, human epidermal growth factor receptor 2-, either Ki-67 high or Progesterone low, Luminal B (human epidermal growth factor receptor +) Estrogen +, human epidermal growth factor receptor 2 +, any Ki-67, any Progesterone) 78.3% (p = 0.534) with a median follow-up of 55.9 months; for patients with triple negative breast cancer it was 73.4% with a median follow-up of 58,1 months, and for patients with human epidermal growth factor receptor 2+ it was 77.1% (p = 0.448) with a median follow-up of 55.5 months. Conclusion. Early initiation of adjuvant chemotherapy is particularly important in patients with advanced- stage breast cancer at diagnosis, and those with trastuzumab- treated triple-negative breast cancer and human epidermal growth factor receptor 2-positive tumors.