Association of a Proposed New Staging System for Folliculotropic Mycosis Fungoides With Prognostic Variables in a US Cohort

Abstract

IMPORTANCE A new cutaneous staging system for folliculotropic mycosis fungoides (FMF) has been purported to better estimate survival compared with the staging system for conventional mycosis fungoides.OBJECTIVE To analyze predictive variables associated with survival and evaluate the effectiveness of the newly proposed staging system for estimating overall survival and disease-specific survival (DSS) in a US cohort. DESIGN, SETTING, AND PARTICIPANTSThis cohort study assessed 195 patients with FMF in the dermatopathology database of the University of California, San Francisco from January 1, 1990, to April 31, 2012, for eligibility. A total of 153 patients were excluded for the following reasons: (1) alternative diagnoses were favored ranging from benign dermatitides to other forms of cutaneous lymphoma; (2) technical problems with slides; and (3) lack of follow-up information. Data were analyzed from January 1, 2018, to August 31, 2020.MAIN OUTCOMES AND MEASURES Kaplan-Meier curves were used to estimate overall survival and DSS for the entire cohort. Possible predictive variables associated with survival were evaluated using Cox proportional hazards regression modeling. Each variable was examined separately, followed by a multiple-variable model. Kaplan-Meier curves were used to estimate overall survival and DSS by subdividing the cohort into early-and advanced-stage cutaneous disease.RESULTS Forty-two patients were included in the analysis (mean age at diagnosis, 55 [range, 8-89] years; 31 men [74%]). For the entire cohort, the estimated 5-year overall survival rate was 89% (95% CI, 79%-99%); 10-year rate, 78% (95% CI, 63%-92%); and 15-year rate, 58% (95% CI, 31%-85%). Estimated 5-and 10-year DSS rates were 89% (95% CI, 79%-99%); 15-year rate, 80% (95% CI, 61%-99%). For overall survival in the multiple-variable Cox proportional hazards regression model, only age was statistically significant (hazard ratio [HR] per 10-year age increase, 3.1; 95% CI, 1.4-7.2; P = .008), whereas for DSS, only cutaneous disease was statistically significant (HR, 11.4; 95% CI, 1.3-103.0; P = .03). When stage stratified, the 5-year estimated overall survival rate for early-stage disease was 96% (95% CI, 89%-103%); 10-year rate, 82% (95% CI, 65%-98%); and 15-year rate, 65% (95% CI, 33%-97%). For advanced-stage disease, the estimated 5-and 10-year overall survival rates were 70% (95% CI, 41%-98%); the 15-year rate, 53% (95% CI, 16%-89%). For early-stage cutaneous disease, the estimated 5-, 10-and 15-year DSS rates were all 96% (95% CI, 89%-103%). For advanced-stage cutaneous disease, the estimated 5-and 10-year DSS rates were 70% (95% CI, 41%-98%); the 15-year rate, 53% (95% CI, 16%-89%). CONCLUSIONS AND RELEVANCECox proportional hazards regression modeling demonstrated cutaneous stage to be the only statistically significant predictive variable associated with DSS. Subdividing FMF into early and advanced cutaneous stages was associated with effective estimation of survival in this cohort. Thus, findings suggest that FMF is a heterogene...

Updated review on prognostic factors in mycosis fungoides and new skin lymphoma trials

“…A recently published study from the United States found that the cutaneous stage was only the significant parameter for predicting DSS. This study also confirmed that FMF is a heterogenous disease divided into early and advanced stages, and poorer prognosis is associated with advanced cutaneous stage 54 …”

Cutaneous T‐cell lymphomas: 2023 update on diagnosis, risk‐stratification, and management

“…Patients with low‐risk (0–1 risk factors) disease experienced superior 5‐year OS (68%) compared with the 5‐year OS observed (28%) among those with high‐risk (3–4 risk factors) disease 11,106–110 . An alternative staging system has been proposed for those with folliculotropic MF and identifies a subset of patients with limited cutaneous involvement and a more favorable prognosis 111,112 . Given the importance of the TNMB classification in risk‐stratification and defining disease burden, the ISCL/EORTC recommends its use in defining the initial, maximum and current burden of disease, which will ultimately play an important role in the selection of either skin‐directed or systemic therapies 93 .…”

Primary cutaneous T‐cell lymphomas in childhood and adolescence

“…However, newer studies have shown that FMF patients can be subdivided into two clinical groups, an early indolent group of patients with follicle‐based patches, flat plaques, keratosis pilaris like and acneiform lesions and an advanced stage group of patients having thick follicle‐based infiltrated plaques and tumors. The latter group is less responsive to therapies and carries a worse prognosis [29–31, 34, 35].…”