Breast cancer genome gives up its secrets

Genetic variants linked to an increased risk of breast cancer are described in two papers published this week in Nature and Nature Genetics. It is hoped that the genome-wide association studies, which collectively draw on data from hundreds of thousands of individuals, might lead to improved screening, earlier detection and better treatments for this disease.

Breast cancer risk is known to be influenced by genetics, and although 105 genetic regions have previously been associated with breast cancer, much of the genetic contribution to risk remains unknown. Douglas Easton and colleagues used a new targeted genotyping array to compare the genomes of women with and without breast cancer, and identify 65 new genetic regions linked to disease risk. Together, these account for 18% of the familial relative risk of developing breast cancer, they report in a Nature paper.

In a Nature Genetics paper, Roger Milne and colleagues focussed on a particular subset of breast cancer, comparing the genomes of women with oestrogen receptor (ER)-negative tumours, carriers of the BRCA1 susceptibility gene, and control subjects. They identify 10 new loci linked to ER-negative breast cancer risk. When the previously reported loci are taken into account, this explains 16% of the familial risk for this breast cancer type. They also note a strong link between the breast cancer risk for BRCA1 mutation carriers and the risk of ER-negative breast cancer in the general population.