Postoperative radiotherapy for cutaneous melanoma of the head and neck region

To assess the efficacy and toxicity of elective-adjunctive radiotherapy given in five 6-Gy fractions to patients with cutaneous melanoma of the head and neck at high risk for local-regional relapse.

From 1983 to August 1992, 174 patients (132 men and 42 women) were enrolled. The ages ranged from 16 to 89 years (median: 54 years). One group (n = 79) received elective irradiation after wide local excision of lesions > or = 1.5 mm thick, or Clark's level IV-V, a second group (n = 32) received adjunctive irradiation after excision of primary lesions plus limited neck dissection, and a third group (n = 63) received irradiation after neck dissection for nodal relapse. Each group had a projected local-regional recurrence rate of approximately 50%. The radiotherapy consisted of five fractions of 6 Gy each, specified at Dmax, delivered twice a week, to a total dose of 30 Gy in 2.5 weeks. Electron beams of appropriate energies were used whenever possible. Junction lines between adjoining fields were moved twice to minimize dose heterogeneity. Patients were seen at regular intervals to assess disease status and therapy-related complications. Patients who relapsed were treated as indicated by the clinical status.

With a median follow-up of 35 months, 111 of 174 patients were alive. The disease recurred above the clavicles only in six patients, at distant sites in 58 patients, and both local-regionally and at distant sites in nine patients. The actuarial 5-year local-regional control (LRC) and survival rates for the whole group were 88% and 47%, respectively. The thickness of the primary lesion, presence of more than three positive nodes, and extracapsular extension did not influence the LRC rate after radiotherapy (range: 85-92%). However, lesion thickness strongly affected the 5-year survival rate of group 1 patients (i.e., 100% for < or = 1.5 mm thick, but Clark's level IV, 72% for > 1.5-4 mm, and 30% for > 4 mm). In groups 2 and 3, the 5-year survival rate of patients with > three involved nodes was lower than that of patients with one to three positive nodes (23% vs. 39%). The acute tolerance to adjunctive radiotherapy was excellent. Late radiation complications were observed in only three patients. These were moderate neck fibrosis, mild ipsilateral hearing impairment, and transient exposure of external auditory canal cartilage.

The safety of this hypofractionated radiotherapy regimen in the management of cutaneous melanoma was established in this study. The overall 5-year actuarial LRC rate of 88% was much higher than that of our historical group and that reported in the literature (50%). The survival rate of patients with lesion of 1.5-4 mm thickness was also higher than that observed in other series. Based on these results a prospective randomized study to further define the role of adjunctive postoperative radiotherapy is planned.