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

Abstract

Purpose: Neurofibromatosis 1 (NF1) is an autosomal dominant condition causedby pathogenic variants of the NF1 gene. Amarkedly increased risk of breast cancer is associated with NF1. We havedetermined the breast cancer survival and risk of contralateral breast cancer inNF1. Methods: We included 142 women with NF1 and breast cancer from five cohortsin Europe and 335 women without NF1 screened for other familial breast cancers.Risk of contralateral breast cancer and death were assessed by Kaplan–Meieranalysis with delayed entry. Results: One hundred forty-two women with NF1 were diagnosed for breastcancer at a median age of 46.9 years (range 27.0–84.3 years) and then followedup for 1235 person-years (mean = 8.70 years). Twelve women had contralateralbreast cancer with a rate of 10.5 per 1000 years. Cumulative risk forcontralateral breast cancer was 26.5% in 20 years. Five and 10-year all-causesurvival was 64.9% (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-NF1age-matched population at increased risk of breast cancer. Conclusion: Women with NF1 have a substantial contralateral breast cancerincidence and poor survival. Early start of breast cancer screening may be a wayto improve the survival.