The new study may bring us closer to personalized treatment for breast cancer.
Study leader Dr. Serena Nik-Zainal, of the Wellcome Trust Sanger Institute in the United Kingdom, and colleagues identified a number of new genes that, when mutated, drive the development of breast cancer tumors.
Additionally, they found that women with breast cancer who possessed the BRCA1 or BRCA2 gene – genes that raise the risk for breast and ovarian cancers – possessed highly individual mutational signatures.
Mutational signatures are patterns of DNA changes that arise in genes as a result of cell damage that accumulates as we age.
“All cancers are due to mutations that occur in all of us in the DNA of our cells during the course of our lifetimes,” explains Prof. Sir Mike Stratton, director of the Wellcome Trust Sanger Institute. “Finding these mutations is crucial to understanding the causes of cancer and to developing improved therapies.”
The researchers say their findings not only shed light on the causes of breast cancer, but they also suggest that each breast cancer patient has an individual cancer genome profile, which may pave the way for personalized breast cancer treatment.
The team’s results are reported across two studies published in Nature and Nature Communications.
Five new gene mutations, 12 new mutational signatures identified
To reach their findings, Dr. Nik-Zainal and her team analyzed the tumors of 560 patients with breast cancer, of whom 556 were women and four were men.
Using whole-genome sequencing, they searched for gene mutations that drive the development of breast cancer tumors, and they looked for mutational signatures in the tumor of each patient.
In total, the researchers identified 93 genes in which a mutation could fuel the development of breast cancer tumors, five of which are newly identified gene mutations. The team also pinpointed 12 new mutational signatures within patients’ tumors.
Furthermore, among women with a BRCA1 or BRCA2 gene mutation, the researchers identified mutational signatures that were highly specific to each patient and that were distinct from other breast cancers.
The researchers believe their results show promise for breast cancer treatment that can be tailored to each individual patient.
“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 personalized healthcare for cancer.”
Dr. Serena Nik-Zainal
Results bring us closer to ‘opportunities for new treatments’
The team also shed light on how the position of mutations within the cancer genome influences breast cancer development.
“We know genetic changes and their position in the cancer genome influence how a person responds to a cancer therapy. For years we have been trying to figure out if parts of DNA that don’t code for anything specific have a role in driving cancer development,” says study co-author Dr. Ewan Birney, of the European Bioinformatics Institute, U.K.
“This study both gave us the first large-scale view of the rest of the genome, uncovering some new reasons why breast cancer arises, and gave us an unexpected way to characterize the types of mutations that happen in certain breast cancers.”
According to the American Cancer Society, around 1 in 8 women in the United States will be diagnosed with invasive breast cancer in their lifetime. This year, around 256,660 American women with be diagnosed with the disease.
Dr. Nik-Zainal and colleagues hope their findings will pave the way for much-needed new treatment options for breast cancer patients.
“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,” says Prof. Stratton.
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