What are the conclusions of the MSLT-1 (Multicenter Selective Lymphadenectomy Trial-1) study regarding melanoma sentinel lymph node biopsy?

From the Guidelines

Sentinel lymph node biopsy (SLNB) is recommended for patients with intermediate-thickness melanomas (1.2-3.5 mm) as it provides important prognostic information and improves disease-free survival, although it does not significantly improve overall survival compared to observation alone. The Multicenter Selective Lymphadenectomy Trial-1 (MSLT-1) study found that patients with intermediate-thickness melanomas who underwent SLNB had improved disease-free survival and melanoma-specific survival if their sentinel nodes contained metastases and they subsequently received complete lymph node dissection 1. The procedure has a high sensitivity (approximately 95%) for detecting nodal metastases with minimal morbidity compared to complete lymphadenectomy.

Key Findings

• The MSLT-1 study showed a significant difference in disease-free survival (DFS) between the SLN biopsy and observation groups for patients with intermediate-thickness melanoma (HR, 0.76; P = .01) 1.
• The study also found that SLNB accurately identified patients with nodal metastases and allowed for early intervention, which reduced the risk of regional nodal recurrence.
• The American Society of Clinical Oncology and Society of Surgical Oncology joint clinical practice guideline recommends SLN biopsy for patients with intermediate-thickness melanomas (Breslow thickness, 1 to 4 mm) of any anatomic site 1.

Recommendations

• SLNB is recommended for staging and prognostic purposes in patients with intermediate-thickness melanomas, and results should be used to guide treatment decisions including adjuvant therapy considerations.
• The procedure involves injecting a radioactive tracer and/or blue dye around the primary melanoma site to identify and remove the first draining lymph node(s) for pathological examination, typically performed at the time of wide local excision of the primary tumor.
• Completion lymph node dissection (CLND) is recommended for all patients with a positive SLN biopsy and achieves good regional disease control 1.

From the Research

MSLT-1 Study Conclusions

The Multicenter Selective Lymphadenectomy Trial-1 (MSLT-1) study provides valuable insights into the role of sentinel lymph node biopsy in melanoma management. Key findings include:

• Sentinel lymph node (SLN) biopsy has become a standard procedure for many patients with melanoma and is recommended in numerous national and professional melanoma guidelines 2.
• The MSLT-1 study confirms the independent and unequalled prognostic value of the SLN, as well as the ability of biopsy-directed management to provide effective regional disease control with the least possible morbidity 2.
• The study also provides strong evidence of a substantial reduction in the risk of melanoma death for patients with intermediate thickness melanomas who harbour occult nodal metastases at the time of presentation 2.

Sentinel Lymph Node Biopsy in Melanoma

Sentinel lymph node biopsy (SLNB) is a minimally invasive surgical procedure that is standard of care for the evaluation of clinically negative regional lymph nodes in patients with cutaneous melanoma. Key points include:

• SLNB is invaluable to clinical decision-making in patients presenting with melanoma, as the presence of metastases dictates patient prognosis and determines the need for further regional disease control or adjuvant therapy 3.
• The indications for SLNB, specifically among patients with thin (<1 mm) or thick (>4 mm) melanomas, remain unclear 3.
• The status of the sentinel node is the strongest predictor of survival in patients with intermediate thickness melanoma, and SLNB compared with observation was associated with a modest survival advantage 4.

Clinical Practice Guidelines

Clinical practice guidelines (CPGs) have been developed outlining recommendations for the role of lymph node biopsy in the management of melanoma. Key findings include:

• The quality of existing CPGs for the indications of SLNB for melanoma is low, with only one CPG achieving a "high" quality rating 3.
• Future guidelines should be pilot tested to evaluate barriers to application and should utilize multidisciplinary guideline development teams that include patients and key stakeholders in addition to clinical experts from all relevant disciplines 3.

Survival Benefits

The MSLT-1 study and other research have investigated the survival benefits of SLNB in melanoma patients. Key points include:

• Subset analysis of the MSLT-1 study showed that for patients with nodal disease and intermediate-thickness melanoma, early treatment following positive SLNB was associated with improved 10-year distant disease-free survival and improved 10-year melanoma-specific survival 5.
• Improved 5-year melanoma-specific survival was associated with SLNB, female gender, absence of ulceration, extremity location, T2 disease, and a negative SNB 4.