Financial toxicity in breast cancer patients receiving regional nodal irradiation: Variation by cancer subtype

Background: We evaluated sociodemographic and clinical predictors of financial toxicity (FT) among patients with breast cancer with higher risk clinical factors warranting regional nodal irradiation (RNI). Methods: Among 183 participants in a clinical trial of conventional vs. hypofractionated treatment with RNI, 125 (68 %) completed a pilot survey of FT measured using the validated Economic Strain and Resilience in Cancer (ENRICh) instrument, scored from 0 (minimal) to 10 (severe) FT. Associations with predictors were evaluated using Pearson correlation coefficients and Kruskal Wallis, Mann-Whitney U, and Jonckheere-Terpstra tests. Predictors of severe FT (ENRICh >= 5) were tested using multivariable logistic regression with odds ratios converted to relative risks (RR). Results: Of the sample, all received RNI, 92 % chemotherapy, 67 % axillary dissection, 26 % mastectomy without reconstruction, and 32 % mastectomy with reconstruction. At a median follow up of 1.48 years, median FT score was 2.13 (IQR 0.93-4.6), with 20.8 % of patients experiencing severe FT. Unadjusted worse FT score was associated with younger age (P = 0.003), Hispanic ethnicity (P = 0.006), lower income (P = 0.02), shorter interval from diagnosis to FT assessment (P = 0.02), and chemotherapy receipt (P = 0.05), but not with breast surgery type (P = 0.42), axillary surgery type (P = 0.33), or pathologic T (P = 0.68) or N stage (P = 0.47). In multivariable analysis, triple negative subtype was the sole clinical factor predicting severe FT (RR = 3.38; 95 % CI 1.48-4.99; P = 0.01). Conclusion: Among patients with breast cancer receiving RNI, triple negative subtype was associated with severe FT, suggesting that tumor receptor subtype may help identify a key breast cancer subpopulation for early FT intervention.