Thick melanomas without lymph node metastases: A forgotten group with poor prognosis

Area of Science:

• Oncology
• Dermatology
• Surgical Pathology

Background:

• Adjuvant therapy is available for melanoma patients with sentinel lymph node (SLN) metastases (pN+).
• However, no adjuvant therapy is established for thick melanomas without SLN involvement (pN-).

Purpose of the Study:

• To assess overall survival (OS) and relative survival (RS) in patients with thick melanomas (>4.0 mm Breslow thickness [BT]) who are either pN- or pN+.
• To compare survival outcomes between thick pN- melanomas and thinner melanomas with positive SLN status (≤4.0 mm pN+).

Main Methods:

• Retrieved clinicopathological data from a Dutch cohort of thick and/or pN+ melanoma patients (2000-2014).
• Compared OS and RS using Kaplan-Meier curves.
• Developed a Cox-regression model to identify OS determinants in >4.0 mm pN- patients.

Main Results:

• In 54,645 patients, 7.2% had >4.0 mm thick melanomas.
• Five-year OS was 70.5% for >4.0 mm pN- and 48.1% for >4.0 mm pN+ melanomas (p < 0.001).
• Five-year OS for ≤4.0 mm pN+ patients (71.5%) was comparable to >4.0 mm pN- patients (p = 0.24).
• Higher age, increased BT, ulceration, and male gender were associated with poor survival in >4.0 mm pN- patients.

Conclusions:

• Thick melanomas without lymph node metastases (pN-) exhibit a poor prognosis, comparable to thinner melanomas with positive lymph node status (pN+).
• Current melanoma treatment guidelines do not adequately account for the high-risk nature of thick pN- melanomas.
• These high-risk patients warrant inclusion in future adjuvant clinical trials.