Secondary cancers, comorbidities and mortality associated with nitrogen mustard therapy in patients with mycosis fungoides: a 30-year population-based cohort study

Abstract

Topical nitrogen mustard is a widely used therapy in patients with mycosis fungoides (MF). However, it remains controversial whether nitrogen mustard therapy is associated with increased risk of secondary cancers and chronic pulmonary diseases in patients with MF. To assess the risk of secondary cancers, comorbidities, mortality and cause-specific mortality in patients with MF treated with nitrogen mustard compared with patients not receiving this treatment. Linking the Danish nationwide registries in a 30-year population-based cohort study, we compared 110 patients with MF from a regional Danish centre using nitrogen mustard treatment with 193 patients from Danish centres not using nitrogen mustard. The two cohorts were compared by Cox regression analysis. Overall, secondary cancers were not significantly increased [hazard ratio (HR) 0.84, 95% confidence interval (CI) 0.46-1.56], and subanalyses showed no significantly increased risk of nonmelanoma skin cancers, malignant melanomas or cancers in the respiratory organs in the nitrogen mustard-treated cohort. Furthermore, we found no significantly increased risk of any category of comorbidity, including chronic pulmonary diseases, in patients treated with nitrogen mustard (HR 0.93, 95% CI 0.48-1.81). Moreover, mortality and cause-specific mortality did not significantly differ between the two cohorts. This study does not support any previous suspicion of increased risk of secondary cancers and chronic pulmonary diseases among patients with MF treated with nitrogen mustard. Furthermore, mortality and cause-specific mortality were not influenced by nitrogen mustard treatment. Thus our findings indicate that topical nitrogen mustard is a safe therapy in patients with MF.