Oestrogen receptor-positive breast cancer and adverse outcome in BRCA2 mutation carriers and young non-carrier patients

Date: Monday, February 8th at 12:30-13:10 in Askja, room N-132

Title: Oestrogen receptor-positive breast cancer and adverse outcome in BRCA2 mutation carriers and young non-carrier patients

Speaker: Laufey Tryggvadóttir Clinical Professor, Faculty of Medicine, University of Iceland. Head of Epidemiological Research, Icelandic Cancer Registry.

Abstract: Oestrogen receptor-positive breast cancer and adverse outcome in BRCA2 mutation carriers and young non-carrier patients

Oestrogen receptor-positive (ER+) breast cancer generally confers a more favourable prognosis than ER-negative cancer, however, a different picture is emerging for BRCA2 mutation carriers and young patients. 

We used nationwide data from population-based registries to study prognostic effects in those two groups. Of all 2817 eligible women diagnosed with breast cancer in Iceland during 1980–2004, 85% had been tested for the Icelandic 999del5 BRCA2 (c.771_775delTCAAA) founder pathogenic variant. We compared breast cancer-specific survival, effects of ER status, other clinical parameters, and treatment, between three mutually exclusive groups: BRCA2-carriers, non-carriers diagnosed 40 years or younger, and older non-carriers. 

Prevalence of the BRCA2 mutation among tested patients <=40 years of age was 21.0%, but it was 5.4% among women diagnosed >40 years of age. For ER+ cancer, breast cancer-specific 15-year survival was 49.7%, 55.2%, and 74.7%, among BRCA2-carriers, young and older non-carriers, respectively, whereas for ER-negative cancer, survival was similar (64.0–69.3%) for all three groups. Neither for BRCA2 carriers nor young non-carriers did tumour grade 3 predict worse survival than did tumour grade 1. 

The adverse outcome for the young cases cannot be explained by the high prevalence of BRCA2 mutations among young patients, as carriers were excluded from the group. Those two clinically important patient groups need special attention with respect to treatment choices, in particular, if diagnosed with ER+ tumours. It is thus advisable to have knowledge of BRCA2 status when treatment decisions are made. Finally, it is important to understand the biological basis for the specific nature of ER+ tumours in young women and BRCA2 carriers.