Results of radiotherapy for epithelial skin cancer of the pinna: the Princess Margaret Hospital experience, 1982-1993.

PURPOSE

To assess the treatment outcome, late toxicity, and prognostic factors for radiotherapy (RT) of carcinoma of the pinna.

METHODS AND MATERIALS

The charts of 313 patients treated between 01/82 and 12/93 were retrospectively reviewed. There were 334 lesions treated: 201 basal cell carcinoma (BCC), 122 squamous cell carcinoma (SCC), and 11 basosquamous carcinoma. RT was most commonly given by orthovoltage X-rays (278 lesions) or electrons (39 lesions). The most frequently used dose prescriptions were 35 Gy in 5 fractions (123 treatments with median field size = 4.9 cm(2)), 42. 5-45 Gy in 10 fractions (67 treatments with median field size = 10.5 cm(2)), and 50-65 Gy in 20-30 fractions (42 treatments with median field size = 81 cm(2)).2 cm. RESUL TS: The actuarial 2- and 5-year local control rates were 86.6% and 79.2 %. Multivariate analysis revealed two factors to be statistically signi ficant for increased local failure: tumor size > 2 cm (hazard ratio [HR] = 2.66, 95% confidence interval [CI] = 1.16-6.08), and a low biological effective dose (BED) (for each decrease of 5 BED units, HR = 1.76, 95% CI = 1.07-2.88). The 5-year actuarial rate of significant Grade 4 late toxicity was 7.3%. Factors statistically significant for this endpoint on univariate analysis were tumor size (p = 0.035), T-stage (p = 0.02), field size (p = 0.05), fraction size (p = 0.003), and BED (p = 0.05).

CONCLUSIONS

RT is an eff ctive treatment option for epithelial skin cancer of the pinna. Large t umor size and low BED were independently statistically significantly ass ociated with increased local failure. Dose-fractionation schedules usin g fraction sizes < 4 Gy may reduce the risk of necrosis and ulceration, particularly for field sizes > 5 cm2.