Influence of Anatomic Locations of T1b Melanomas and Patient Age on Outcomes

May 2024 | Volume 23 | Issue 5 | 306 | Copyright © May 2024


Published online April 19, 2024

doi:10.36849/JDD.7667

Margaret Y. Huang BSa, Alessandra Chen MDb, Claudia Quarshie BSa, Rahul Masson BSa, Gabrielle Barajas BSa, Gene Kim MDb,c, Brittney DeClerck MDb,c, Mark S. Swanson MDd, Gino K. In MD MPHe, Niels Kokot MDd, Trevor A. Pickering PhDf, Jenny C. Hu MD MPHb

aKeck School of Medicine of University of Southern California, Los Angeles, CA 
bDepartment of Dermatology, Keck School of Medicine of University of Southern California, Los Angeles, CA
cDepartment of Pathology, Keck School of Medicine of University of Southern California, Los Angeles, CA
dCaruso Department of Otolaryngology, Head and Neck Surgery, Keck School of Medicine of University of Southern California, Los Angeles, CA
eDivision of Oncology, Department of Medicine, USC Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA
fDivision of Biostatistics, Department of Preventive Medicine, Keck School of Medicine of University of Southern California, Los Angeles, CA

Abstract
Background: There are no guidelines on when to more strongly recommend sentinel lymph node biopsy (SLNB) for T1b melanomas.
Objective: To examine whether anatomic locations of T1b melanomas and patient age influence metastases.
Methods: We conducted a retrospective study using data from two hospitals in Los Angeles County from January 2010 through January 2020.
Results: Out of 620 patients with primary melanomas, 566 melanomas were staged based on the American Joint Committee on Cancer 8th edition melanoma staging. Forty-one were T1b, of which 13 were located on the face/ear/scalp and 28 were located elsewhere. T1b melanomas located on the face/ear/scalp had an increased risk of lymph node or distant metastasis compared with other anatomic sites (31% vs 3.6%, P=0.028). For all melanomas, the risk of lymph node or distant metastasis decreased with age of 64 years or greater (P<0.001 and P=0.034). For T1b melanomas, the risk of distant metastasis increased with increasing age (P=0.047).
Limitations: Data were from a single county. 
Conclusion: T1b melanomas of the face/ear/scalp demonstrated a higher risk of lymph node or distant metastasis and may help guide the recommendation of SLNB, imaging, and surveillance. Younger patients may be more strongly considered for SLNB and older patients with T1b melanomas may warrant imaging. 

J Drugs Dermatol. 2024;23(5):306-310. doi:10.36849/JDD.7667

INTRODUCTION

Melanoma constitutes 3% of all skin cancers, but accounts for 65% of skin cancer deaths.1 The incidence of melanoma is increasing, with approximately 100,000 new diagnoses annually, of which more than two-thirds are thin melanomas categorized as American Joint Committee on Cancer (AJCC) tumor stage T1 having a Breslow depth 1 millimeter (mm) or less.2,3 The most recent AJCC 8th edition melanoma staging has a new tumor category, T1b, which includes thin melanomas of Breslow depth <0.8 mm with ulceration or 0.8-1 mm with or without ulceration. The National Comprehensive Cancer Network (NCCN) clinical practice guidelines for cutaneous melanoma, which was subsequently updated, recommends that melanomas categorized as T1b should be considered, but not necessarily recommended, for sentinel lymph node biopsy (SLNB). A recent National Cancer Database study found that the new AJCC staging system resulted in overutilization of SLNB in patients with a melanoma tumor category of T1b, while another study noted a low number of SLNB in patients with T1b melanomas.4-6 These findings highlight that the use of SLNB for patients with T1b melanomas varies considerably, indicating a critical need for additional selection tools to guide the appropriateness of SLNB in these melanomas. 

The anatomic location of thicker melanomas, with a Breslow depth >1 mm, is an important predictor of positive sentinel 
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