Comments and controversies: sentinel node and lymphadenectomy in melanoma: staging or therapeutical?: what to expect from the multicenter selective lymphadenectomy trial-1 results in melanoma?

Melanoma nodal management in Ontario the year after the 2012 American Society of Clinical Oncology and Society of Surgical Oncology guideline

Background

In 2012 in the United States, the American Society of Clinical Oncology and the Society of Surgical Oncology (asco/sso) published a joint guideline about indications for sentinel lymph node biopsy (slnb) in cutaneous melanoma. The guideline supported completion lymph node dissection (clnd) for all patients with positive sentinel nodes. We examined the rates and predictors of slnb and clnd for melanoma patients in Ontario (population 13.6 million) after publication of that guideline.

Methods

We used the Ontario Cancer Registry to identify patients diagnosed with cutaneous melanoma in 2013. Patient records were linked to prospectively maintained health administrative databases to obtain details for each patient, including surgical procedures.

Results

Of the 3298 patients with melanoma identified in Ontario in 2013, 1973 (59.8%) could be analyzed. Most of that group (n = 1227, 62.2%) underwent local excision alone; 746 (37.8%) had a slnb. The slnb was performed in 13.9%, 67.8%, 62.6%, and 47.2% of patients with T1, T2, T3, and T4 primary melanomas respectively. In multivariate analysis, receipt of slnb was positively associated with younger age (<80 years), higher T stage, and a non-head-and-neck primary. Of the patients who had a slnb, 136 (18.2%) were found to be node-positive. A clnd was performed in 82 of those patients (60.3%).

Conclusions

In Ontario, only two thirds of patients with intermediate-thickness melanomas (T2, T3) underwent slnb as recommended by the asco/sso guideline. Use of slnb was less frequent for patients with a head-and-neck primary and higher for younger patients (<80 years). The rate of clnd after a positive slnb was also low relative to the guideline recommendation.

Surgical Management and Adjuvant Therapy for High-Risk and Metastatic Melanoma

Wide local excision is considered routine therapy after initial diagnosis of primary melanoma to reduce local recurrences, but it does not impact survival. Sentinel node staging is recommended for melanomas of intermediate thickness, but it has also not demonstrated any indisputable therapeutic effect on survival. The prognostic value of sentinel node staging has been long established and is therefore considered routine, especially in light of the eligibility criteria for adjuvant therapy (trials). Whether completion lymph node dissection after a positive sentinel node biopsy improves survival is the question of current trials. The MSLT-2 study is best powered to show a potential benefit, but it has not yet reported any data. Another study, the German DECOG study, presented at the 2015 American Society of Clinical Oncology (ASCO) Annual Meeting did not show any benefit but is criticized for the underpowered design and insufficient follow-up. There is no consensus on the use of adjuvant interferon in melanoma. This topic has been the focus of many studies with different regimens (low-, intermediate-, or high-dose and/or short- or long-term treatment). Adjuvant interferon has been shown to improve relapse-free survival but failed to improve overall survival. More recently, adjuvant ipilimumab has also demonstrated an improved relapse-free survival. Overall survival data have not yet been reported due to insufficient follow-up. Currently, studies are ongoing to analyze the use of adjuvant anti-PD-1 and molecular targeted therapies (vemurafenib, dabrafenib, and trametinib). In the absence of unambiguously positive approved agents, clinical trial participation remains a priority. This could change in the near future.