BRCA1 and triple-negative breast carcinoma: However, this does not take into account the fact that the 10% threshold is not clearly reached in women with an isolated breast cancer and no family history [15], In a large study of 1824 cases [15], only 18/209 (8.6%) women with sporadic triple negative breast cancer diagnosed aged 40–49 years had an identifiable mutation in BRCA1/2. This is supported by a detection rate of only 8/94 (8.5%) in sporadic triple negative cases <50 years in the present study although the 95% confidence intervals do overlap with 10–8.5% (95% CI 2.9–14.2%).