melanoma

Three clinical features identify thin melanomas at high risk of recurring within two years: age over 65, ulceration, and mitotic rate

Thin melanomas — classified as T1, meaning the tumor is ≤1mm deep — are generally considered low-risk and treated with surgery alone. Yet thin melanomas account for more than 25% of melanoma deaths. Identifying which thin melanomas will recur quickly is a major unresolved clinical challenge.

This large multi-site study compared 310 patients whose T1 melanoma recurred within 2 years to 132 patients whose melanoma recurred after 10+ years. Three factors independently predicted rapid recurrence: age over 65, ulceration (tumor surface breakdown), and a mitotic rate of ≥1/mm². Head and neck location and lentigo maligna subtype were associated in single-variable analysis but dropped out in multivariable modeling.

Most rapid recurrences (73%) were locoregional — nearby rather than distant — suggesting there may be a window for more aggressive local treatment in high-risk patients.

Key Findings

Age >65, ulceration, and mitoses ≥1/mm² independently predicted T1 melanoma recurrence within 2 years
73% of rapid recurrences were locoregional, not distant metastases
442 patients from 14 sites included — largest such cohort to date
Head/neck location and lentigo maligna subtype were significant in univariable but not multivariable analysis
Study identifies a high-risk T1 subgroup that may need more intensive surveillance or adjuvant therapy

Implications

These findings could directly change how thin melanomas are managed. Patients over 65 with ulceration or high mitotic rate may warrant sentinel lymph node biopsy, closer surveillance, or adjuvant therapy — currently not standard for T1 disease. This provides the clearest evidence yet for a risk-stratified approach to thin melanoma management.

Caveats

Preprint — not peer reviewed. Retrospective study design with data from 14 sites — potential selection bias toward referred/complex cases. Late recurrence group (≥10 years) may not be the ideal comparator for identifying all rapid-recurrence risk factors. Molecular/genomic data not included. Does not establish causality or test an intervention.

Source: medRxiv — 2026-04-06

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