2497 - Prospective Patient-Reported Outcomes (PRO) Regarding Skin Toxicity from Hypo-Fractionated Regional Nodal Irradiation (RNI) following Mastectomy and Lumpectomy

Purpose/Objective(s): Moderate Hypo fractionation is increasingly utilized for RNI with breast and chest wall treatment; however, there is still limited data available on the patient’s experience. Our institution prospectively collects PRO on all patients receiving radiation on an IRB approved protocol since 2022. This study aims to assess patient experience with skin changes from moderate hypo-fractionation RNI with chest wall or breast radiation.

Materials/Methods: We identified patients in the PRO database who received unilateral RNI with either chest wall (CW) +/- reconstructed breast (RB) or native breast (B) radiation with moderate hypo-fractionation from January 2022 to May 2024. Radiation was delivered with 3DCRT or IMRT using either 4005 cGy over 15 fractions (F) or 4256 cGy in 16 F to contoured target volumes. RNI included the undissected axilla, internal mammary and supraclavicular nodal regions. Patient-reported outcomes regarding skin toxicity were measured using the Breast-Q Breast Cancer Core Checklist (post-operative) Version 2.0, adverse effects of radiation module, administered at baseline, 1 month post RT, and one-year post-RT. Each patient scored six items on a scale of 1 -Not at all, 2- a little, 3 - a lot, resulting in a total skin toxicity score ranging from 6 to 18. Toxicity severity was designated as follows: total score of 6 = none, 7 to 8 = mild, > 8 to 12 = moderate, and total scores > 12 =severe. Patients were stratified based on presence of reconstruction, no reconstruction or native breast. Descriptive statistics were used to analyze the data, and the mean and median skin toxicity scores were calculated at each time point for each stratum.

Results: A total of 84 patients were identified who had moderate hypo-fractionation RNI; 44% (n= 37) to CW, 50% (n=42) CW/RB, and 6% (n= 5) to B and completed PROs. There were 82 females and two males. The median age was 57 years (range: 47 -96). 39%(n=33) had IMRT and 61% (n=51) had 3DCRT. No meaningful toxicity was reported by patients at baseline. Similar average PRO scores were seen at 1 month and 1 year post radiation demonstrating mild (occurring “a little”); mean score 7.65 at 1month vs 7.3 at 1 year. In the small cohort of RNI with native breast appeared to have lower score at 1- and 12-months post RT (see table 1). Table 1: The results of PRO skin toxicity is summarized in the table below: (n=84).

Conclusion: In a prospectively collected database of PRO’s, skin toxicity severity after moderately hypo fractionated RNI post mastectomy or lumpectomy was on average predominantly none to mild. Highest average scores were seen at one month after radiation completion.