Necrosis following radiotherapy for carcinoma of the pinna

Radiation therapy is often the preferred modality of treatment for carcinoma of the pinna because it avoids the cosmetic defect of surgery. However, radiation oncologists are sometimes reluctant to irradiate the ear because of the risk of subsequent necrosis. The goal of this study was to establish the long-term disease control and necrosis rates following irradiation of the external ear.

A retrospective analysis was undertaken of 138 courses of curative radiotherapy given to 128 patients for biopsy-proven basal (70 courses), squamous (62 courses), or mixed (6 courses) tumors of the pinna between January 1, 1982, and December 31, 1991, at the Kingston Regional Cancer Center.

The median age of the patients was 73 (range 43-94) and the median size of the tumors was 12 mm (range 3-50 mm). Treatment was given using orthovoltage X rays (79) or electrons (59). The most common dose prescription was 35 Gy/5 fractions; total doses ranged from 17.50 to 64 Gy. The median follow-up is 58 months (range 6-149). The actuarial 5-year local control rate is 93%; the actuarial necrosis rate at 5 years is 13%. Most necroses healed with conservative management; only two patients required surgery for necrosis. We analyzed the following factors as possible predictors of radiation necrosis: patient age, size of lesion, histology, fraction size, total dose, overall time, and beam energy. Only daily fraction sizes > 6 Gy (p = 0.0093) and treatment times < 5 days (p = 0.0053) were significantly associated with an increased risk of necrosis.

To reduce the risk of necrosis, radiation therapy for external ear cancer should be given using protracted fractionation.