Prognosis of increasing percentages of lesional body surface area in early stage mycosis fungoides

Abstract

Background: Early-stage mycosis fungoides (MF) is often an indolent disease with a favourable prognosis, though 25% progress to advanced stages. Patients with ≥10% body surface area (BSA) involvement have a worse prognosis than those with <10%, but the impact of other BSA levels remains unclear.

Objectives: This study aimed to determine whether additional BSA cut-off points higher than 10% provide additional prognostic information.

Methods: This study included 401 patients with early-stage MF of the Leiden University Medical Centre and a validation cohort of 602 patients from the PROCLIPI database. Different percentages of lesional BSA were analysed both in the total groups and in subgroups of patients with only patch-stage disease or with patch-plaques-stage disease, and correlated with survival.

Results: Both cohorts showed a progressive and gradual decline in overall survival (OS) with each 10% increase in BSA, reaching a 5-year OS below 50% (LUMC) or 70% (PROCLIPI) for BSA ≥40%. In both cohorts, patients with a BSA of 10%-39% had a significantly worse OS than those with a BSA of less than 10%, but a significantly better OS than those with ≥40%. These differences in OS were only found in patients with patches and plaques and not in patients with only patches.

Conclusions: An additional cut-off point of 40% involved BSA has prognostic significance in patients with early patch/plaque-stage MF and may be included in future updates of the clinical staging system. In these patients, systemic therapies should be considered.