What Is the Actual Rate of Acute Skin Toxicity in Women Undergoing Adjuvant Radiation Therapy for Early Breast Cancer? Preliminary Results of a Single Institution Phase II Study.

Abstract

The accurate rate of acute skin toxicity experienced by women undergoing adjuvant radiation therapy as part of Breast-Conservative Therapy (BCT) for early breast cancer is lacking in the literature. The limited available publications place the rate of grade II or higher at around 40-50%, while the rate of grade III moist desquamation is reported to be around 15-20%. In this prospective phase II study we evaluated the actual rate of acute skin toxicity in these patients and correlated that with patient characteristics.Material and method: Patients with breast separation of less than 25 cm were treated with Canadian hypofractionation regimen (42.4 Gy in 16 fractions) while patients with 25 cm or more were treated with the usual adjuvant breast fractionation (50 Gy in 25 fractions). As part of the institution's standard of care all patients were advised to apply hydrating cream from day one of the radiation therapy (RT) (Glaxal Base and Aveeno were most commonly used). The National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0 (CTCAE) was used for grading of the acute skin toxicity. To avoid subjective interpretation of the CTCAE, Each patient was graded by two radiation oncologist at week 0 week 2, week 3, last day of treatment and 2 weeks after treatment completion. Univariant and multivariant analysis were performed to evaluate the contribution of patient characteristics to the toxicity.Results: At the time of this analysis 85 patients with a median age of 57 (range 33-80) have completed their adjuvant RT. Of these 72% received the hypofractionated regimen and 69% had an extra boost of 10 Gy in 4 fractions to the tumor bed either because of younger age (less than 60) or close margins. 37 patients (44%) received chemotherapy prior to RT and 30 patients (35%) were active smokers. The volume of the breast varied significantly among the patients, median volume of 729 cc (range 246-2271).Acute skin toxicity was 18% at 2 weeks with only 2 patients (3%) having grade II, 54% at 3 weeks with only 5 patients (6%) having grade II and 82% at the last day of the treatment with 18 patients (21%) having grade II or higher. Only 2 patients had grade III and no grade IV skin toxicity was observed. The rate of residual skin reaction at 2 weeks post RT was 41% with only 7% grade II and no grade III. Multivariant analysis associated hypofractionation with decreased acute skin reaction at the last day of the treatment, 100% vs. 71% (p=0.0204), and active smoking with delayed skin healing at 2 weeks post RT 25% vs. 52% (p=0.0373). There was no correlation between the volume of the breast and skin toxicity at any of the evaluation timelines.Conclusion: The actual rate of acute skin toxicity in women undergoing adjuvant radiation therapy for BCT is considerably overstated in medical literature. Hypofractionation is associated with decreased acute skin reaction and active smoking is correlated with delayed healing. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4109.