Abstract 76: Rate of moist desquamation in patients receiving radiation for breast cancer after mastectomy versus breast conserving surgery.

Abstract

Abstract OBJECTIVE: Although skin toxicity is expected to be more severe in the setting of post-mastectomy radiation (PMRT) compared to breast conserving surgery + intact breast radiation (BCT), the actual incidence of moist desquamation (MD) in patients treated with PMRT has not been well quantified. We prospectively determined rates of MD in patients treated with PMRT compared to BCT and identified risk factors for the development of MD. MATERIALS/ METHODS: 284 breast cancer patients enrolled on two parallel prospectively managed observational studies to assess skin reaction to RT (one in the setting of BCT and the other PMRT) were included in this analysis. All received tangential photons to the intact breast or chest wall (CW) following definitive surgery, with a dose of 45-50 Gy to the breast/CW +/- supraclavicular nodes (SCV). BCT patients had a 10 Gy lumpectomy cavity boost. PMRT patients received daily 0.5 cm bolus with a 10 Gy scar boost. Skin toxicities and rates of MD were rated by the treating physician on a weekly basis during RT, using the CTCAE v3.0 scale. Logistic regression analysis was used to assess risk factors associated with MD. RESULTS: Overall, 19% were black, 64% Hispanic white, and 17 % non-Hispanic white/other. Patients receiving PMRT were younger (median age 51.5 vs 57, p<.001), and had more advanced stage (0% vs 20.4% stage 0, 7% vs 46.9% stage I, 32.8% vs 26.1% stage II, and 60.3% v. 6.6% stage III, p<.0001), but there was no difference between the groups with respect to race, ethnicity, body mass index (BMI), or smoking status. In the BCT group, 23% of patients developed MD vs 55.2% in the PMRT group (p<0.0001). Other factors predictive of MD were increasing BMI (17.3% in BMI <25, 31.1% in BMI 25-29.9,37.2% in BMI >30, p=0.011), and increasing breast cancer stage (21.7% stage 0, 24.5% stage I, 29.5% stage II, 49% stage III, p=0.018). On multivariate analysis, the use of PMRT (OR 3.84, 95% CI 1.76-8.87, p=0.001) and increasing BMI (OR 2.42, 95% CI 1.10-5.30 (p=0.028) for BMI 25-29.9 vs <25; OR 3.10, 95% CI 1.46-6.59 (p=0.003) for BMI ≥30 vs <25) retained statistical significance as risk factors for MD, but stage was no longer significant. There was no difference in rate of MD by race or ethnicity. CONCLUSIONS: The rate of MD is more than double in patients receiving PMRT vs BCT, 55.2% vs 23%, even when accounting for increasing stage and BMI. This information is important in counseling our patients regarding the potential toxicities of adjuvant radiation treatment for breast cancer. Citation Format: Jean L. Wright, Cristiane Takita, Isildinha Reis, Wei Zhao, Jennifer J. Hu. Rate of moist desquamation in patients receiving radiation for breast cancer after mastectomy versus breast conserving surgery. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 76. doi:10.1158/1538-7445.AM2013-76