Relationships between the changes of skin temperature and radiation skin injury

Background: Radiation skin injury (RSI) causes changes in skin temperature, but detailed information on the thermographic responses is currently lacking. We investigated thermographic patterns after radiotherapy. We hypothesized that skin temperature may be used as a diagnostic and early predictor of RSI severity.Method: All breast cancer patients received radiotherapy after unilateral postmastectomy. The contralateral supraclavicular area served as control, and the frontal thermal image of torso was taken by a thermal infrared imager weekly. We defined areas of interest on bilateral symmetrical supraclavicular area, and analyzed the difference of average and maximum skin temperature (DST_average and DST_max) between them. The extent of the weekly variation in DST (DSTW) was calculated using a mathematical formula to represent a trend of skin temperature change. RSI and symptoms related to RSI were scored from baseline to 2 weeks after the end of radiotherapy.Results: Forty-one patients were enrolled in this study. In comparison to the baseline, the DST_average and DST_max increased significantly over time during radiotherapy (p < .05). The onset of DST increase was accompanied by the onset of radiation dermatitis, and the maximal DST also appeared at the peak of Radiation Therapy Oncology Group (RTOG) and symptom scores. Radiation dose, DST_average, burning-feeling and pulling were the independent variables affecting RTOG score according to multivariate analysis (p < .001, p < .034, p < .001, p < .001). Patients with DSTW_average >1.223 or DSTW_max >1.114 in second week showed a late higher dermatitis score (RTOG score ≥2).Conclusion: This study confirmed that RSI was associated with thermographic response. Our results suggested that the follow-up observations of skin temperature during radiotherapy could provide the objective evaluation criteria and prediction methods for RSI.