Low Incidence of Symptomatic Lymphedema Following Hypofractionated Radiation Therapy for Early-stage Breast Cancer

Purpose/Objective(s): Limited data exist regarding the development of breast cancer-related lymphedema (BCRL) following hypofractionated whole breast irradiation (h-WBI) for early-stage breast cancer. The purpose of this study was to evaluate the rate of symptomatic BCRL in patients treated with h-WBI and to attempt to correlate factors predictive for BCRL development.Materials/Methods: 289 patients with early-stage breast cancer were treated with h-WBI from 2007-2013. Following breast-conserving surgery, adjuvant RT was delivered to the whole breast utilizing a hypofractionated regimen of 4256 cGy in 16 fractions. No lumpectomy cavity boost or third (supraclavicular) field was used. Toxicity was assessed at each follow-up. Upper extremity BCRL was scored loosely based on the CTCAE v3.0: 1 = no BCRL, 2 = mild BCRL, 3 = moderate BCRL, and 4 = severe BCRL. No formal arm measurements were taken.Results: Median follow-up was 2.7 yrs (range 0-6). Median age at diagnosis was 68 yrs (31-89; 92% post-menopausal). Histology was DCIS in 24% (n=71), invasive ductal in 64% (n=186), invasive lobular in 6% (n=16), and other (medullary, colloid, tubular) in 6%. T-stage was Tis in 24%, T1 in 65%, and T2 in 11%, with a median tumor size of 11 mm (1-70 mm). The majority of patients had grade 1 (42%) or 2 (44%) histology. Of the 137 patients who had sentinel lymph node (SLN) sampling, the median number of LN removed was 1 (0-6). 16% of patients who had SLN sampling underwent a completion axillary lymph node dissection, with a median of 2 nodes removed (0-24). Initial surgical margins were positive in 12% of patients (n=33) and close in 29% (n=80). 89 of the patients with inadequate margins underwent re-excision, resulting in a final margin clearance rate of 96%. Final margins were positive in only 1% of patients. ER/PR was positive in 92%/79%, and Her2/neu was negative in 97%. Toxicity data was available for 97% of patients (n=281). The incidence of symptomatic BCRL was < 1%. Given the very low number of events, further correlation for predictors was not possible.Conclusions: The incidence of symptomatic BRCL for patients undergoing h-WBI was very low in this cohort of patients, which could be due to our detection method or because of small numbers of LN removed. The development of BCRL typically occurs within the first 3 yrs post-treatment, indicating a sufficient follow-up length in our cohort. However, because ours was a gross assessment of symptomatic lymphedema with no formal extremity measurements, the accuracy of evaluating BCRL using this method is limited. Current practice in the lymphedema clinic at our institution involves bilateral measurements taken at 5 different points along the upper extremity, pre- and post-treatment. While the current study suggests that h-WBI is safe with regards to avoiding the development of BCRL, prospective evaluation utilizing a more thorough and systematic approach should be considered.

SSK23-06

Low Incidence of Symptomatic Lymphedema Following Hypofractionated Radiation Therapy for Early-stage Breast Cancer