Association between skin phototype and radiation dermatitis in patients with breast cancer treated with breast-conserving therapy: Suntan reaction could be a good predictor for radiation pigmentation

摘要

The purpose of this study was to evaluate the significance of skin phototype (suntan or sunburn type) in association with radiation dermatitis in patients with breast cancer who underwent postoperative radiotherapy after breast-conserving surgery because phototype could predict sunlight reaction. We divided patients into two phototypes (58 suntan/darkening and 28 sunburn/reddening types) according to self-reports before radiotherapy. We examined skin color changes in 86 patients who underwent breast-conserving surgery followed by 50 Gy/25 fractions (median) of radiotherapy with or without boost radiation (10 Gy/5 fractions). Color change was assessed according to CIE L*a*b* space, which is defined by the Commission Internationale de l'éclairage (CIE) in 1976 for quantitative color assessment. The patients were also assessed by individual typology angle (ITA°; indicator of skin color calculated by L x a x b x space) and Common Terminology Criteria for Adverse Event v3.0 (CTCAE v3). Radiation therapy changed all values except the b value, and the suntan type showed a greater darkening response associated with radiation dermatitis than did the sunburn type in terms of ITA° value change (p = 0.04), whereas the sunburn type did not show higher a* value (reddening). By CTCAE v3 classifications, a Grade 2 reaction appeared in 14% sunburn patients and in 31% of the suntan group, respectively (p = 0.16). Suntan type predicted higher pigmentation associated with radiation dermatitis. Self-reported phototype has the potential to be a good predictor of skin sensitivity to radiation exposure for clinical screening.