Subcutaneous fibrosis after whole neck irradiation.

Abstract

To identify the risk factors for moderate to severe subcutaneous fibrosis after whole neck irradiation. We analyzed 233 cases of patients who had undergone whole neck irradiation with 4-MV X-ray or 8-10-MeV electrons, or both, and had been followed with regard to their skin condition for at least 1 year. The prescribed dose to the whole neck ranged from 19.2 to 72.4 Gy (median 50). The skin-absorbed dose was specified as that at a depth of 4.1 mm (d4.1-mm(depth)), and a biologically equivalent dose (BED) of d4.1-mm(depth) was also estimated (BED(1.8) 4.1-mm(depth)). Univariate analysis revealed that previous neck dissection, concurrent chemotherapy, corticosteroid administration as a part of chemotherapy, fractionation, and BED(1.8) 4.1-mm(depth) were significant prognostic variables. Multivariate analysis showed that BED(1.8) 4.1-mm(depth) and previous neck dissection were the only prognostic variables for moderate to severe subcutaneous fibrosis. A high dose to a 4.1-mm depth of the skin and a history of neck dissection were identified as the predominant risk factors for moderate to severe subcutaneous fibrosis after whole neck irradiation. A subcutaneous dose should be considered in radiotherapy treatment planning involving the whole neck, especially in cases in which patients have undergone previous neck dissection.