Abstract P1-10-06: Hypofractionated nodal radiotherapy (RT) did not increase arm morbidity compared to conventional fractionated nodal RT

Abstract

Abstract Purpose: Regional nodal radiation therapy (RT) can cause adverse arm symptoms and lymphedema. Hypofractionation (HF), defined as >2 Gy/fraction, improves convenience but whether it increases arm morbidity is unclear. This study evaluates patient-reported arm symptoms in women treated with HF compared to conventional fractionation (CF) RT (defined as ≤2Gy/fraction). Materials / Methods: Provincial cancer registries were used to identify subjects who received 3D, CT-planned nodal RT for pT1-3 pN0-2 M0 breast cancer from 2007-2009 in British Columbia and 2008 – 2010 in Alberta, Canada. Treatment eras were selected to enable sufficient follow-up time to develop late arm symptoms. Following research ethics approval, eligible patients were mailed an explanation letter and an externally validated, Self-reported Arm Symptom Scale (SASS) survey. The SASS included 8 questions about arm symptoms, with responses on a 5-point Likert scale regarding arm/hand problems (numbness, pain, stiffness, immobility and swelling), and 5 questions related to activities of daily living (ADL). Clinicopathologic characteristics and SASS scores were compared between HF vs. CF nodal RT cohorts using non-parametric analysis (on ordinal and scale responses) and binned chi-squared analysis (comparison for responses of 1 vs. > 1). Results: 800/1759 eligible patients returned a completed survey (45.5%). Upon detailed chart review of responders, 92 cases with recurrence or metastasis were excluded. The remaining 708 cases formed the study cohort. Of these, 406 (57%) patients received HF RT (modal dose/fractionation 40 Gy/15 fractions (fx) and 45 Gy/20 fx), and 302 (43%) received CF RT (45 Gy/25 fx, 48-50 Gy/25 fx, and 50.4 Gy/28 fx). A boost was delivered to the breast in 22% of subjects, equally by fractionation group (p=0.31). Median time interval since RT completion was 5.67 years. The mean age at diagnosis was 59.0 in HF vs 53.8 years in CF-treated cohorts (p<0.001). The mean # positive (n=3) and excised (n=12) nodes were similar between fractionation cohorts (p=0.44). Primary tumor size was marginally larger in the CF group (2.8 vs. 2.7 cm, p=0.03). 42.9% of patients were treated with partial mastectomy with no significant difference in fractionation (p=0.54). Overall, 602 (75.3%) patients received chemotherapy. A trend toward increased use of CF after chemotherapy was observed (78.8% vs. 72.7%, p=0.07). The mean sums of responses for the arm symptoms / ADL components of the SASS were 12.5 / 7.6 vs. 13.3 / 7.9 for the HF and CF groups respectively (p=0.17 / 0.85). On analysis of individual questions, the CF group had a higher prevalence of self-reported symptoms, including shoulder stiffness (p=0.04), trouble moving the arm (p=0.02), and ability to reach overhead (p<0.01). There was no difference in self-reported arm swelling between the two groups (p=0.57). Conclusion: Hypofractionated nodal RT was not associated with an increase in patient-reported arm symptoms or disability compared to conventional fractionated nodal RT. Subjects treated with CF RT reported more disability in certain aspects of arm and shoulder function. These data support the use of shorter fractionation when the regional lymph nodes are part of the therapeutic target. Citation Format: Leong N, Truong P, Tankel K, Kwan W, Weir L, Olivotto I. Hypofractionated nodal radiotherapy (RT) did not increase arm morbidity compared to conventional fractionated nodal RT [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-10-06.