33755 Patterns and prognosis of distant metastases of melanoma subtypes in the Surveillance, Epidemiology, and End Results database

Abstract

Background: Metastatic melanoma has poor prognosis with patterns of distant metastases that are incompletely explored. We aim to describe the distribution and prognosis of melanoma subtypes using the Surveillance, Epidemiology, and End Results (SEER) database. Methods: Patients with metastatic melanoma were identified in SEER diagnosed from 2010 to 2016. Melanoma subtypes encompassed malignant melanoma, NOS (MM), nodular melanoma (NM), superficial spreading melanoma (SSM), acral lentiginous melanoma (ALL), and lentigo maligna melanoma (LMM). ANOVA and Fisher exact tests assessed for differences in clinical characteristics by melanoma subtype and primary site of lesion. Fine-Grey competing risk regression was performed on MM, SSM, and NM subtypes to assess for prognosticators of cancer-specific mortality. Results: We identified 2492 patients with metastatic melanoma (63.5% MM, 24.4% NM, 12.2% SSM, 2.2% ALM, and 1.9% LMM). MM and NM had a higher propensity for brain metastases, liver metastases, and lung metastases than other subtypes. Patients with ALM had a predilection for bone and lung metastases compared with other sites of metastasis. When stratified by site, head and neck and trunk lesions for all subtypes (except ALM) had a greater propensity for lung metastases compared with lesions on the extremities. Furthermore, lesions on the trunk had a higher proportion of liver metastases than lesions on other primary sites. On regression analysis, lung and liver metastases had poorer prognosis in MM, SSM, and NM. Conclusions: Our analysis demonstrates that melanoma subtypes have a differential preference for sites of distant metastases.