Cutaneous Stage Predictive of Survival in Folliculotropic Mycosis Fungoides

In patients with folliculotropic mycosis fungoides (FMF), age is associated with overall survival, and advanced-stage disease is associated with disease-specific survival, according findings from a study published in JAMA Dermatology.

Researchers sought to analyze predictive variables associated with survival and evaluate the effectiveness of a newly proposed staging system for estimating overall survival and disease-specific survival (DSS) in patients with FMF. A total of 42 patients with FMF (mean age at diagnosis, 55 [range, 8-89] years; 31 men [74%]) from the dermatopathology database of the University of California, San Francisco, were included in the analysis.

The investigators found that the estimated 5-year overall survival rate of the cohort was 89% (95% CI, 79%-99%), the 10-year rate was 78% (95% CI, 63%-92%), and the 15-year rate was 58% (95% CI, 31%-85%). The estimated 5- and 10-year DSS rates were 89% (95% CI, 79%-99%), and the 15-year rate was 80% (95% CI, 61%-99%).

In the multiple-variable Cox proportional hazards regression model regarding overall survival, only age was statistically significant (hazard ratio [HR] per 10-year age increase, 3.1; 95% CI, 1.4-7.2; P =.008). For DSS, only cutaneous disease was statistically significant (HR, 11.4; 95% CI, 1.3-103.0; P =.03).

The 5-year estimated overall survival rate for early-stage disease when the data were stage stratified was 96% (95% CI, 89%-103%), the 10-year rate was 82% (95% CI, 65%-98%), and the 15-year rate was 65% (95% CI, 33%-97%).

For advanced-stage disease, the estimated 5- and 10-year overall survival rates were 70% (95% CI, 41%-98%), and the 15-year rate was 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%), and the 15-year rate was 53% (95% CI, 16%-89%).

The findings suggest a more favorable survival in patients with FMF compared with other initial reports, according to the study authors. “To our knowledge, this outcome represents the first report of a more favorable survival in patients with FMF in a US cohort,” they stated.

Study limitations include biases associated with the retrospective design and the relatively small sample. Large, prospective, multicenter studies following well-defined inclusion and exclusion criteria would be helpful for future studies, according to the researchers.

“In this cohort study of patients with FMF, cutaneous stage was the most effective variable associated with survival among all variables tested,” stated the investigators. “We subanalyzed overall survival and DSS by cutaneous stage, finding meaningful clinical differences, and this is the first US study, to our knowledge, to demonstrate this difference. Therefore, we hold that this system is helpful and advocate its use for patients with FMF.”

The findings support the theory that FMF is not intrinsically an aggressive mycosis fungoides variant “because patients with early-stage cutaneous disease have a prognosis essentially equivalent to that of early-stage conventional mycosis fungoides,” noted the study authors. “However, a subset of patients with advanced cutaneous stage FMF have an aggressive course. This cutaneous staging scheme is of practical utility in the clinical setting because it will give patients with FMF a more realistic sense of their prognosis.”

Reference

Charli-Joseph Y, Kashani-Sabet M, McCalmont TH, et al. Association of a proposed new staging system for folliculotropic mycosis fungoides with prognostic variables in a US cohort. Published online December 9, 2020. JAMA Dermatol. doi:10.1001/jamadermatol.2020.4372