Breast cancer in six women with neurofibromatosis type 1

Neurofibromatosis type I (NF1) is associated with certain types of malignancy including childhood cancers, neuroendocrine tumours and sarcomas. An association with breast cancer has been suggested but few cases have been reported. We report six cases of breast cancer occurring in women less than 60 years of age with NF1, most of whom had locally advanced and poorly differentiated breast cancer on presentation. Karyotypic analysis revealed no abnormalities in these patients, including chromosome 17q where both the NF1 and BRCA1 genes are located. Since radiosensitivity has been linked to cancer predisposition in breast and some other cancer types, we examined clinical and in vitro radiosensitivity in the six patients. Three of the women showed increased in vitro radiosensitivity and two of four that received radiotherapy showed an adverse clinical response. Analysis of the ataxia-telangiectasia gene in these individuals by the protein truncation test showed that none were likely to be mutation carriers.