Purpose: Although regional nodal irradiation (RNI) improves outcomes in breast cancer (BC) patients, it is associated with increased toxicity. Therefore, controversy still exists surrounding its indications. The purpose of this study was to evaluate and compare patient-reported acute fatigue in elderly BC patients with and without regional nodal radiation (RNI).
Methods: Elderly breast cancer patients (≥ 65 years) treated with adjuvant radiotherapy (RT) between 2012 and 2017 were identified from a prospective database. The validated Edmonton Symptom Assessment System-revised (ESAS-r) questionnaire, which assesses fatigue, was completed prior to (baseline), during, at end of RT and first follow-up (3-6 months). Symptoms were rated on a 10-point Likert scale, with higher scores indicating higher fatigue. Patient's treatment characteristics were also recorded prospectively. This was a retrospective study which identified elderly breast cancer patients who had received adjuvant radiation, completed ESAS-r prospectively and provided research consent for using ESAS-r. Patients were divided into two cohorts: those who received RNI (cohort 1) and those who did not (cohort 2). A minimal clinically important difference (MID) was defined using an anchor of ≥ 1-point compared to baseline. The proportion of patients reporting a change in fatigue at the end of RT was evaluated. To test the robustness of the results, dynamic changes of fatigue scores over time were further compared between the cohorts using a general linear mixed model (GLMM) after assuming individual patient with random effect. Univariate and multivariable logistic regression were conducted to assess the association between RNI and MID after adjusting for potential confounders. In addition to longitudinal analysis, a multivariable mixed effect model was developed to determine the association of RNI with fatigue after adjusting for potential confounders. A two-tailed p value ≤ 0.05 was considered statistically significant.
Results: Of the 1198 patients, 859 had provided research consent and completed the ESAS-r at baseline and any other time-point and were included in the longitudinal analysis (cohort 1 = 159, cohort 2 = 700), while 637 (cohort 1 = 135, cohort 2 = 502) patients completed the ESAS-r at baseline and end of radiotherapy and were included in the anchor-based analysis. Mean age at diagnosis was similar between the groups: cohort 1; 71.5 ± 5.7 vs. cohort; 2 72 ± 5.4 years (total 71.8 ± 5.5). Overall, cohort 1 had higher stage (Stage 3: 32.7% vs 3.6%, p < 0.001) and reception of chemotherapy (68.6% vs. 16.1%, p < 0.001). Mean baseline fatigue was higher for cohort 1 vs. 2 (2.7 ± 2.5 vs. 2.1 ± 2.3, p = 0.006). On univariate and multivariable analyses, RNI was not associated with an increased odd of MID for fatigue at the end of RT (44% vs. 47%; OR 0.89, 95% CI 0.61-1.30, p = 0.56). After adjusting for confounders (age, duration of RT, endocrine therapy), treatment with RNI was not associated with increased odds of worse fatigue at the end of RT (OR 1.33, 95% CI 0.85-2.10, p = 0.22). Higher baseline fatigue (OR 0.86, 95% CI 0.79-0.92, p < 0.001) and receipt of chemotherapy had decreased odds (OR 0.50, 95% CI 0.32-0.86, p = 0.001) and were the only factors associated with decreased odds of MID. Dynamic changes showed a significant worsening of fatigue scores over time (p < 0.001) towards the end of RT and recovery at first follow-up (p < 0.001) with no difference between the cohorts (p = 0.38); both experienced parallel worsening of fatigue levels over time (cohort*time p = 0.71 and cohort*time2p = 0.78). On multivariable analysis earlier stage, the absence of chemotherapy and higher baseline depression were independent predictors of worse fatigue scores over time (p = 0.01, p = 0.003, and p = 0.02, respectively).
Conclusion: The addition of RNI in elderly BC patients is not associated with a significant worsening of patient-reported fatigue. Predictors of acute fatigue will enable shared decision making between patients and clinicians.
Keywords: Breast cancer; Fatigue; Regional nodal radiation.