Background: The authors sought to evaluate trends in survival among a population-based group of patients with mycosis fungoides, in response to informal evidence of improved prognosis and concerns about the influence of detection bias on incidence data.
Methods: Data used in this study were drawn from the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute, which includes 9 population-based cancer registries. Together, these registries cover approximately 10% of the U.S. population and have tracked the survival of all mycosis fungoides patients who were registered during the years 1973-1992. Data included follow-up through 1994.
Results: There was a total of over 10,000 person-years of follow-up for the 1633 patients studied. Relative survival changed little after 11 years, at which point it was 66%. Advanced age and black race were associated with poorer survival. The prognoses of Asian and Hispanic patients were slightly but not significantly worse than those of whites, and there were no significant geographic differences related to prognosis. The survival of married women was superior to that of other gender and marital-status groups. Prognosis did improve substantially over the 20-year period of study.
Conclusions: Mycosis fungoides is usually not a fatal disease, although the mortality risk is substantial. The authors quantified various prognostic factors and documented an improved prognosis over the 20-year period of study. The data from this study raise concern about possible detection bias in incidence data. These data are also consistent with the concept that beyond 11 years after diagnosis, this disorder has relatively little impact on the risk of death.