Do Molecular Subtypes of Breast Cancer Affect Outcomes Following Hypofractionation or Conventional Fractionation Radiation Therapy
Year: 2019
Type: article
Study design: Observational Study
Abstract: Introduction Molecular subtypes of breast cancer (BC) are well-established prognostic markers in early-stage BC patients. The addition of radiation therapy (RT) to breast-conserving surgery has improved outcomes in this patient population, with conventional fractionation (CF) and hypofractionation (HF) regimens displaying comparable morbidity and mortality. However, most studies have not taken into account molecular subtype. Thus, it is still unknown if outcomes are similar between CF and HF for each molecular subtype. Herein, the effects of molecular subtype on the efficacy of CF and HF radiotherapy regimens for early-stage BC patients receiving adjuvant RT was investigated. Methods A retrospective review of stage I/II BC patients who received surgical intervention (breast conservation surgery or mastectomy) followed by RT at UNMC between 2010 and 2017 was conducted. Demographics, tumor characteristics, treatment data (course and dose of radiotherapy), and outcomes information (progression and survival) were collected. Cumulative incidence function and Kaplan-Meier testing were used to assess recurrence and survival, respectively. Variables were then further analyzed using univariate and multivariable COX proportional hazard models. Results In total, 311 patients met the inclusion criteria, including 211 CF and 100 HF patients. Patients undergoing HF were of lower stage and grade, but increased age. Rates of locoregional recurrence, distant recurrence, and survival were similar between cohorts. When stratifying based on molecular subtype, no differences in recurrences or survival were observed. On multivariable analysis, only stage was a significant predictor of distant failure and survival. Conclusions Although patient numbers were low, these findings suggest that HF and CF are equally efficacious in controlling locoregional recurrence in early stage BC patients. Thus, a hypofractionated regimen for radiation therapy should be considered an option regardless of molecular subtype in early stage BC following breast conserving surgery.
Source: DigitalCommons@UNMC
Author: Richard Sleightholm
Language: English
Subfield: Cancer Research
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2965357362