First genetic link discovered to difficult-to-diagnose breast cancer sub-type
Scientists have identified the first genetic variant specifically associated with the risk of a difficult-to-diagnose cancer sub-type accounting for around 10-15 per cent of all breast cancer cases.
The largest ever study of the breast cancer sub-type, called invasive lobular carcinoma, gives researchers important clues to the genetic causes of this particular kind of breast cancer, which can be missed through screening.
The research was co-led by The Institute of Cancer Research, London, King’s College London, and Queen Mary University of London. It used gene chip technology and complex statistical analysis to compare the DNA of more than 6,500 women with invasive lobular cancer with the DNA of more than 35,000 women without the disease.
The study involved more than 100 research institutions from around the world and was funded by several organisations in the UK including Breast Cancer Campaign, Cancer Research UK, Breakthrough Breast Cancer and the ICR.
A woman with the genetic variant, called rs11977670, was found to have a 13 per cent higher chance of developing invasive lobular cancer than a woman without it. The variant is close to two genes on chromosome 7: BRAF, a known cancer-causing gene, and JHDM1D, which is involved in the activation and deactivation of other genes.
The discovery of the genetic variant, in conjunction with other markers, could help in the development of future genetic screening tools to assess women’s risk of developing invasive lobular cancer, and also gives researchers important new clues about the genetic causes of the disease and a related precursor to cancer called lobular carcinoma in situ.
Invasive lobular carcinoma develops in the lobes of the breast that produce milk and can be particularly difficult to diagnose, because the cancer often does not form a definite lump and may not show up on mammograms. As a result, women with this type of cancer tend to be diagnosed when the cancer is more advanced and more difficult to treat.
As well as looking for new genetic risk factors, the researchers also evaluated 75 variants previously linked with breast cancer overall. They found that most of these were associated with risk of invasive lobular cancer specifically, as well as overall breast cancer risk. The study also showed for the first time that genetic factors for invasive breast cancer can also predispose to lobular carcinoma in situ.
Institute of Cancer Research
