Radiation Therapy Practice Patterns for Treatment of Curative Breast Cancer in a Large Tertiary Health Care System

Abstract

Purpose: Disparities have been reported in women treated for breast cancer (BrCa). This study examines potential disparities in BrCa treatment offered based on race and age from a multicenter radiation department. Methods and Materials: We identified 901 patients with early stage BrCa who received curative intent radiation therapy (RT) between 2004 and 2018. Data extracted included age, race, disease stage, treatment technique, treatment dates, and fractionation. Patient race was recorded as Asian, Black, Hispanic, and White. RT technique delivered was classified as a type of external beam radiation therapy or brachytherapy/intraoperative radiation therapy. Fractionation schema were defined as 1) standard fractionation, 1.8-2 Gy; 2) hypofractionation, 2.5-2.67 Gy; 3) accelerated partial breast irradiation (APBI), 3.4 Gy – 4.25 Gy, and 4) intraoperative radiation therapy, single dose of 20 Gy. Stage was recorded using TNM staging. The χ2 test and a multivariable multinomial logistic regression model were used to assess whether patient characteristics, such as age, race, or stage influenced fractionation schemes. Results with 2-sided P values < .05 were considered statistically significant. Results: Racial composition of the study was 13.8% Asian, 22% Black, 29%, White, and 35.1% Hispanic. Mean age was 61 and was divided into 4 age range groups: 30 to 49 (n = 160), 50 to 59 (n = 231), 60 to 69 (n = 294), and ≥70 years (n = 216). In addition, 501 patients (56%) received hypofractionation, 342 (38.8%) received standard fractionation, and 58 (7.1%) received APBI, respectively. For all groups, hypofractionation became more common over time. Age ≥70 years was associated with 9 times higher odds of APBI and 14 times higher odds of hypofractionation, compared with age 30 to 49 years. After adjusting for the other predictors in a multivariable multinomial logistic regression model, the race distribution differed among the 3 groups (P = .03), with a smaller percentage of Hispanics and higher percentage of blacks in the standard group. Conclusions: This study of a diverse cohort of patients with breast cancer failed to identify treatment differences associated by race. The study found an association between age and hypofractionation.