Predictive factors of radiation-induced skin toxicity in breast cancer patients.

Background: To assess the factors affecting the incidence of radiation-induced dermatitis in breast cancer patients treated with adjuvant 3 D conformal radiotherapy by the analysis of dosimetry and topical treatments.

Methods: Between September 2002 and July 2009, 158 breast cancer patients were treated with adjuvant 3 D conformal radiotherapy after undergoing surgery. Before November 2006, 90 patients were subjected to therapeutic skin care group and topical corticosteroid therapy was used for acute radiation dermatitis. Thereafter, 68 patients received prophylactic topical therapy from the beginning of radiotherapy. The two groups did not differ significantly in respect of clinical and treatment factors. Furthermore, the possible mechanisms responsible for the effects of topical treatment on radiation-induced dermatitis were investigated in vivo.

Results: The incidence of radiation-induced moist desquamation was 23% across 158 patients. Higher volume receiving 107% of prescribed dose within PTV (PTV-V107%; >28.6%) and volume receiving 110% of prescribed dose within treated volume (TV-V110%; > 5.13%), and no prophylactic topical therapy for irradiated skin, were associated with higher incidence of acute radiation dermatitis. The protective effect of prophylactic topical treatment was more pronounced in patients with TV-V110% > 5.13%. Furthermore, using irradiated mice, we demonstrated that topical steroid cream significantly attenuated irradiation-induced inflammation, causing a decrease in expression of inflammatory cytokines and TGF-beta 1.

Conclusion: TV-V110% > 5.13% may be an important predictor for radiation induced dermatitis. Prophylactic topical treatment for irradiated skin can significantly improve the tolerance of skin to adjuvant radiotherapy, especially for patients with higher TV-V110%.