Breast cancer in neurofibromatosis 1: survival and risk of contralateral breast cancer in a five country cohort study

Purpose:Neurofibromatosis 1 (NF1) is an autosomal dominantcondition caused by pathogenic variants of theNF1gene. Amarkedly increased risk of breast cancer is associated with NF1. Wehave determined the breast cancer survival and risk of contralateralbreast cancer in NF1.Methods:We included 142 women with NF1 and breast cancerfrom five cohorts in Europe and 335 women without NF1 screenedfor other familial breast cancers. Risk of contralateral breast cancerand death were assessed by Kaplan–Meier analysis with delayed entry.Results:One hundred forty-two women with NF1 were diagnosedfor breast cancer at a median age of 46.9 years (range 27.0–84.3years) and then followed up for 1235 person-years (mean=8.70years). Twelve women had contralateral breast cancer with a rate of10.5 per 1000 years. Cumulative risk for contralateral breast cancerwas 26.5% in 20 years. Five and 10-year all-cause survival was64.9% (95% confidence interval [CI]=54.8–76.8) and 49.8% (95%CI=39.3–63.0). Breast cancer–specific 10-year survival was 64.2%(95% CI=53.5–77.0%) compared with 91.2% (95% CI=87.3–95.2%) in the non-NF1 age-matched population at increasedrisk of breast cancer.Conclusion:Women with NF1 have a substantial contralateralbreast cancer incidence and poor survival. Early start of breastcancer screening may be a way to improve the survival.