A critical assessment of adjuvant radiotherapy for inguinal lymph node metastases from melanoma

Background: Although patients with inguinal or pelvic lymph node (LN) metastases from melanoma may develop regional recurrence after dissection, the role of adjuvant radiotherapy remains controversial. Methods: The medical records of 40 patients with inguinal and/or pelvic lymph node metastases from melanoma were reviewed retrospectively. Indications for adjuvant radiotherapy included the following nodal characteristics: extracapsular extension, LNs ≥3 cm in diameter, ≥4 involved LNs, and LN recurrence after prior nodal surgery. Thirty-seven of 40 patients underwent formal LN dissection. Three patients had only local excision of gross disease for recurrence after prior dissection. All patients received radiation to a median dose of 30 Gy at six Gy/fraction delivered twice weekly. Results: With a median follow-up time of 22.5 months, the 3-year actuarial distant metastasis-free and overall survival rates were 35% and 38%, respectively. The 3-year regional control rate was 74%. Univariate analyses of patient, tumor, and treatment characteristics failed to reveal any association with distant metastasis-free survival, overall survival, or regional control. Regional failures occurred in nine patients; seven of these were isolated dermal failures within the field of irradiation. Only two patients (5%) had LN basin recurrences; one of these patients also developed dermal recurrence. Fifteen of 40 patients developed lymphedema; in seven of these, lymphedema was present before initiation of radiation therapy. Conclusions: Radiation may prevent recurrence of nodal disease in patients at high risk for regional failure, but in-field dermal recurrences may sometimes occur (8 of 40, 20%). Treatment-related lymphedema and death from metastatic melanoma were common.