Five new genes associated with breast cancer have been uncovered by the largest-ever study to sequence the whole genomes of breast cancers. The study also found 13 new mutational signatures that influence tumor development.

The findings also uncover what genetic variations exist in breast cancers and where in the genome they occur. The results also provide evidence that breast cancer genomes are highly individual.

This international collaboration was led by Dr Serena Nik-Zainal of the Wellcome Trust Sanger Institute. The study involved analysis of 560 breast cancer genomes; 556 from women and four from men, and included breast cancer patients from around the world, including the USA, Europe and Asia.

Each person’s cancer genome is an exhaustive historical record of the genetic changes acquired throughout their life. As a person develops from a fertilised egg into adulthood, the DNA in their cells collect genetic changes along the way.

In fact, human DNA is constantly being damaged by things in the environment or simply from wear and tear in the cell. These mutations form patterns, or mutational signatures, that scientists can detect and read for clues about the causes of cancer.

Personalised Healthcare For Cancer

Dr Nik-Zainal’s team searched for mutations that embolden cancers to grow, and looked for mutational signatures in each patient’s tumor.

They found that women who carry the BRCA1 or BRCA2 gene, and so have increased risk of developing breast and ovarian cancer, had whole cancer genome profiles that were highly distinctive from each other and were also very different to other breast cancers. This discovery could be used to classify patients more accurately for treatment.

Dr Nik-Zainal says:

“In the future, we’d like to be able to profile individual cancer genomes so that we can identify the treatment most likely to be successful for a woman or man diagnosed with breast cancer. It is a step closer to personalised healthcare for cancer."

Professor Sir Mike Stratton, Director of the Wellcome Trust Sanger Institute, said:

“All cancers are due to mutations that occur in all of us in the DNA of our cells during the course of our lifetimes. Finding these mutations is crucial to understanding the causes of cancer and to developing improved therapies.

This huge study, examining in great detail the many thousands of mutations present in each of the genomes of 560 cases brings us much closer to a complete description of the changes in DNA in breast cancer and thus to a comprehensive understanding of the causes of the disease and the opportunities for new treatments."

Nik-Zainal S et al. Landscape of somatic mutations in 560 breast cancer whole genome sequencesis Nature 2016 DOI: 10.1038/nature17676

Photo: Ed Uthman/Flickr

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