Breast cancer detection among Irish BRCA1 & BRCA2 mutation carriers: a population-based study.

Background: High-risk breast cancer screening for BRCA1/2 mutation carriers with clinical breast exam, mammography and MRI has reported sensitivity of 100 %, but BRCA1/2 mutation carriers still present with interval cancers.

Aims: We investigated the presentation and screening patterns of an Irish cohort of BRCA1/2 mutation carriers with breast cancer.

Materials And Methods: BRCA1/2 mutation carriers with breast cancer were identified in this retrospective cohort study. Records were reviewed for BRCA1/2 mutation status, demographics, screening regimen, screening modality, stage and histology at diagnosis.

Results: Fifty-three cases of breast cancer were diagnosed between 1968 and 2010 among 60 Irish hereditary breast ovarian cancer (HBOC) families. In 50 of 53 women, the diagnosis of breast cancer predated the identification of BRCA1/2 mutations. Breast cancer detection method was identified in 47 % of patients (n = 25): 80 % (n = 20) by clinical breast exam (CBE), 12 % by mammography (n = 3), 8 % by MRI (n = 2). Fourteen women (26 %) developed a second breast cancer. Ten of these patients (71 %) were involved in regular screening; 50 % were detected by screening mammography, 20 % by MRI and 30 % by CBE alone. Six patients (43 %) had a change in morphology from first to second breast cancers. There was no change in hormone receptor status between first and second breast cancers.

Conclusion: In this cohort of Irish BRCA1/2 mutation carriers, compliance with screening was inconsistent. There was a 30 % incidence of interval cancers occurring in women in high-risk screening. Preventive surgery may be a more effective risk reduction strategy for certain high-risk women.