Survival Following Neoplastic Disease in Individuals With Neurofibromatosis 1—A National Danish Population‐Based Cohort Study

ABSTRACT

Population‐based evidence on cancer survival in individuals with neurofibromatosis 1 (NF1) remains limited. We compared survival following a first neoplasm in individuals with NF1 to that of the general Danish population and stratified on age, sex, and potential survival‐related factors, including cancer stage and comorbidity. Using the Danish Cancer Registry, we identified 428 individuals with NF1 and 392,885 without NF1, all diagnosed with a first neoplasm (1977–2022). We estimated survival using Kaplan–Meier methods, assessed neoplastic and nonneoplastic mortality, and evaluated prior inpatient disease burden in adults (aged 20–69 years) based on hospital diagnoses 10 years to 6 months before neoplasm diagnosis. Among children (aged 1–19 years), NF1 was overall associated with better 5‐year survival (NF1: 87.3% [81.1%–93.5%], non‐NF1: 78.7% [77.9%–79.6%]), due to better survival following central nervous system (CNS) neoplasms. In adults, 5‐year survival was lower in NF1 compared to the general population (57.0% [51.3%–62.6%] vs. 69.2% [69.0%–69.3%]). NF1 adults more often presented with stage IV breast (17.2% vs. 6.3%) and gastrointestinal cancers (52.5% vs. 37.7%). Among adults with no prior inpatient diagnoses, 5‐year survival was poorer in NF1 (60.1% [51.3%–68.9%] vs. 72.1% [71.9%–72.3%]). Five‐year neoplastic mortality was higher in NF1 adults (39.4% [33.8%–45.0%] vs. 27.7% [27.6%–27.9%]). In conclusion, individuals with NF1, particularly adults, have poorer cancer survival than the general population. Differences in cancer type and stage at diagnosis contribute but do not fully explain the excess mortality, indicating that factors beyond general health status may play a role.