Abstract P3-08-09: Clinical and Pathological Characteristics of Breast Cancer in Women with Neurofibromatosis Type 1

Abstract

Abstract Background: Neurofibromatosis type 1(NF1) is an autosomal dominant genetic disorder affecting 1 in 3,000 individuals worldwide. Risk of cancer, including breast cancer, is increased, as NF1 is a tumour suppressor gene. There is limited data on the characteristics of breast cancer in individuals with NF1. Objectives: To study the clinical and pathological characteristics of breast cancer in women with NF1. Methodology: Patients with both NF1 and breast cancer were identified retrospectively from hospital records as well as prospectively when seen at National Cancer Centre Singapore (NCCS) and Singapore General Hospital (SGH). All women had histologically proven breast cancer and fulfilled at least 2 of the 7 criteria developed by the NIH Consensus Conference for clinical diagnosis of NF1. Germline NF1 mutation sequencing is being performed on patients with blood specimens available. Details on patient demographics, tumour grade, stage, receptor status and clinical outcome were evaluated. The pathological characteristics of NF1-associated breast cancer were then compared to sporadic breast cancers in our 2001–2004 cohort, with a focus on grade and HER2 positivity rate. Results: We identified 13 women with NF1 and breast cancer seen at our institutions from 2001 to present date. Average age of breast cancer diagnosis for women testing positive was 48 years (range 30–64). All 13 patients had invasive ductal carcinoma; of which 5 were stage 3 or 4 at diagnosis. To date, 4 out of 12 patients with stage 1–3 breast cancer have relapsed. Grade, estrogen, progesterone and HER2 receptor status were fully available for 12 patients. Ten out of 12 tumours (83%) were grade 3, compared to 45% (705/1578) among our sporadic breast cancers (p = 0.007). Eight out of 12(67%) NF1-associated breast cancers were HER2 positive (IHC 3+ or FISH positive), compared to 27% (367/1367) in sporadic cancers (p = 0.002). Two other NF1-associated tumours were triple negative, and two were hormone receptor positive and HER2 negative. Six out of 12 (50%) NF1-associated cancers were estrogen receptor (ER) positive, compared to 67% (1124/1689) in sporadic cancers (p = 0.2). Conclusion: Our findings suggest that NF1-associated breast cancer tends to be more aggressive, with a higher frequency of grade 3 and HER2 positive tumours compared to sporadic breast cancer. Further genomic profiling of these tumours (in progress) may elucidate the role of NF1 in breast cancer. This may also have implications for sporadic tumours with somatic NF1 mutations in individuals without NF1. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-08-09.