Juhi Purswani, MD
New York University School of Medicine
New YORK, NY
Purpose/Objective(s): Existing scales to assess radiation dermatitis (RD) in breast cancer patients (pts) undergoing radiotherapy (RT) are subjective and do not account for variability in skin of color (SOC). For instance, CTCAE criteria, reliant on the assessment of erythema does not include pigmentation change in the scale. Our aim was to evaluate skin changes using a spectrophotometer according to RT fractionation in parallel with physician-graded RD and describe changes specific to SOC.
Materials/
Methods: In this phase I/II trial, pts with stage I-III breast cancer undergoing conventional whole breast/chest wall (CF: 50Gy/25 fractions), hypofractionated (HF: 40.5Gy/15 fractions) and ultrahypofractionated partial breast RT (UH: 6Gy/5 fractions) were enrolled. SOC was defined by the Fitzpatrick scale (FS) as light (FS 1/2), intermediate (FS 3/4) or dark (FS 5/6). 3 skin readouts using the Commission International de l’Eclairage (CIELAB) color system (l*: 0=black, 100=white; a*: negative values=green, positive values=red; b*: negative values=blue, positive values=yellow) were measured with a spectrophotometer at baseline, weekly, 10 days, 1 and 12 months post RT. ANOVA analyses were used to compare the mean changes from baseline to 10 days post RT in l*, a* and b* skin readouts in quadrant of the tumor bed among the 3 RT fractionation groups with adjustment for the 3 multiple outcomes, which was the primary endpoint. Physician-graded RD was measured using the CTCAE.
Results: From 2022-2024, 60 pts were enrolled (15% CF, 47% HF and 38% UH). 25% were in light, 50% in intermediate and 25% in dark SOC groups. At 10 days post RT, there was more skin darkening with CF vs HF vs UH (mean ?l* [SD]: -8.11 [7], -5.58 [3.94] and -3.21 [1.78], respectively, p=0.011). There was more skin reddening with CF vs HF vs UH in the location of highest-grade RD (?a*: 2.16 [3.54], -0.9 [2.37] and 0.68 [1.38], respectively, p=0.009). Overall less skin reddening was observed in dark SOC (?a*: 0.67 [dark], 3.08 [intermediate] and 2.17 [light], p=0.005) and there was a trend to more skin darkening in intermediate and dark SOC vs light (?l*: -5.11 [dark], -6.13 [intermediate] and -2.88 [light]). In pts with dark SOC who underwent CF, HF and UH mean ?l* (SD) was -6 (5.86), -5.02 (4.06) and -3.7 (NA) and mean ?a*(SD) was 0.67 (1.95), -1.03 (2.42) and 0 (NA), respectively. With regard to physician-rated RD, there was more grade 2/3 RD with CF (88% CF, 39.3% HF, 8.7% UH). Rate of grade 1 RD declined with SOC (73.3% light, 66.7% intermediate and 13.3% dark) and grade 2/3 RD increased with SOC (26.7% light, 30% intermediate and 53.3% dark). Grade 2/3 breast pain was highest in dark SOC (0% light, 0% intermediate and 20% dark).
Conclusion: Objective skin changes and differences in toxicity were demonstrated according to fractionation and SOC. SOC experienced a high rate of grade 2/3 RD and breast pain; however, objective skin reddening was not as apparent as in light or intermediate pts. The CTCAE likely under-captures RD in SOC and must be modified to better measure RD in SOC.