Researchers from the M. D. Anderson Cancer Center have reported that adjuvant radiation therapy (RT) improves local control of melanoma following therapeutic lymph node dissection for lymph node-metastatic disease and may improve disease-specific survival. The details of this retrospective study were published early online in Cancer on August 21, 2009.[1] 

Surgery is the primary treatment of patients with Stage I-III melanoma. However, high recurrence rates have prompted attempts to develop effective adjuvant therapies after primary local and regional surgical interventions. The relative resistance of melanoma to radiation therapy as well as a wide range of chemotherapeutic agents has led clinical oncologists to evaluate different post-surgical adjuvant therapies in patients with advanced melanoma. Radiation therapy has not been extensively explored as adjuvant therapy for Stage I-III melanoma because of the belief that melanoma is a very radio-resistant cancer. Currently, the only FDA approved adjuvant therapy for Stage I-III melanoma is high-dose interferon-alfa.

A previous study from the M. D. Anderson Cancer Center reported that excellent disease-free survival was observed in patients with Stage I-III head and neck melanomas who were treated with adjuvant radiation therapy. These authors concluded: “Adjuvant radiotherapy resulted in a 10-year regional control rate of 94%. Complications for all patients were rare and manageable when they did occur. The authors recommend adjuvant irradiation for patients with extracapsular extension, lymph nodes measuring 3 cm in size or larger, the involvement of multiple lymph nodes, recurrent disease, or any patient having undergone a selective therapeutic neck dissection.”

The current study included 615 patients with melanoma who underwent therapeutic lymphadenectomy for clinical lymph node metastasis of the cervical, axillar, inguinal, and epitorchlear areas.  One hundred-six patients underwent surgery alone, and 509 patients underwent surgery plus RT. The median follow-p was five years. Regional control was 93%, 91%, and 69% for patients with cervical, axillary, and inguinal lymphadectomy plus RT. Corresponding control rates for therapeutic lymphadectomy alone were 43%, 48%, and 69%, respectively. Distant metastases-free survival and disease-specific survival were affected by the number of positive lymph nodes and the number of lymph nodes removed. Disease-specific survival was also affected positively by primary tumor thickness and adjuvant RT. These authors concluded: “Adjuvant RT was associated with improved regional lymph node basin control compared to therapeutic lymphadectomy alone in patients with high-risk, clinically advanced, lymph node-metastatic melanoma. Although this is a regional therapy, adjuvant RT also may have an impact on disease-specific survival”.

Comments: These authors also suggest that the role of adjuvant RT can only be elucidated completely by a randomized controlled trial. However, such a trial may be difficult to perform given the grim outlook for this disease. Furthermore, many patients would probably opt for RT.

Reference: