Evaluating the benefits of adjuvant radiotherapy after therapeutic lymphadenectomy for melanoma patients with positive lymph nodes

The present study compared the outcomes between patients with clinically advanced melanoma spread to the lymph nodes who underwent therapeutic lymphadenectomy (TL) alone, or TL with regional radiation therapy.

Melanoma spread to the nearby lymph nodes is also called lymph-node metastatic melanoma. The treatment for these patients involves a wide excision (surgery to remove the melanoma as well as a margin of normal skin around it) and the surgical removal of the nearby groups of lymph nodes (also called therapeutic lymphadenectomy or TL). Sometimes, in more advanced cases, or in patients with high risk of recurrence (return of the cancer), other treatments may also be given, such as radiation, biological therapy or chemotherapy. 

This study included 615 patients who underwent TL for clinical lymph-node metastatic melanoma. All patients underwent a wide excision for the primary melanoma. 17% of patients had surgery alone, while 83% also received adjuvant (or post-operative) regional radiation therapy. About one third of all patients also received systemic (or whole body) biological therapy, chemotherapy or the two combined (as biochemotherapy). Parameters measured were overall survival, disease-specific survival, or DSS (the percentage of patients who survived melanoma for a defined period of time), as well as regional and distant recurrence rates.

After a median follow up of 5 years, only 10.2% of patients who underwent TL+RT developed regional recurrence compared to 40.6% patients in the TL alone group. Similarly, the distant recurrence rate was lower in the TL + RT group compared to the TL alone group (55.4% versus 73.6%). The overall survival and DSS 5 years after treatment were 44% and 48% respectively. Only 16% of patients developed treatment-related side-effects that needed medical attention. More patients from the combined therapy group (TL+RT) developed side-effects compared to the TL alone group (20% versus 13%). The most common treatment-related side effect was lymphedema (an abnormal buildup of lymphatic fluid that causes swelling, most often in the arms or legs, sometimes occuring after extensive lymph node removal). 

In conclusion, this study showed that in patients with clinically advanced, high-risk, lymph-node metastatic melanoma, the addition of RT to TL lowers the risk of regional recurrence. Also, RT may also improve survival from melanoma in these patients. 

The main drawback of this study is that it looks back at patients who have been treated in the past (retrospective study) rather than following the patients throughout their treatment and determining their outcomes (prospective study). Retrospective studies are considered to provide weaker statistical evidence.