University of Cambridge breast cancer study gives hope of early monitoring for women with BRCA1 mutations
University of Cambridge researchers have shown that they can detect changes in breast tissue long before tumours appear.
The work is still at an early stage, but it is hoped it could in future enable screening of women with BRCA1 gene mutations to monitor changes to their breast cells.
This could inform who would benefit from preventative surgery and give reassurance to those who can wait.
The study, funded by Cancer Research UK, identified what may have been the earliest changes that occur in healthy breast tissue before it turns cancerous.
Researchers found breast cells with the BRCA1 gene mutation undergo changes similar to those normally seen in late pregnancy.
Many women who discover they have this faulty gene choose to have preventative mastectomies as BRCA1 mutations significantly increase the risk of developing breast cancer at a younger age.
However, not all women who have BRCA1 mutations will go on to develop cancer, so for some the life-changing surgery may be unnecessary or could be delayed until early warning signs are detected.
Dr Sara Pensa co-author and Senior Research Associate at the Department of Pharmacology and Wellcome-MRC Stem Cell Institute, said: “One of the mysteries surrounding BRCA gene mutations is how they increase a woman’s risk of cancer so dramatically in the breast tissue, as opposed to say the kidneys or lung. It seems that certain pathways in breast cells that are usually switched on by hormones during pregnancy are triggered by BRCA1 mutations and cause the cells to grow out of control.”
The researchers, led by Karsten Bach and Dr Pensa, analysed the mammary tissue of 15 mice at various ages carrying the BRCA1 mutation to look for changes before tumours developed.
They found BRCA1 mutation triggered certain pathways to be switched on in a type of stem cell called a luminal progenitor breast cell, usually only activated during pregnancy. These messages tell the progenitor cell to turn into alveolar cells, which make up the chambers in the breast where milk production takes place in late pregnancy.
Karsten, co-author on the study and PhD student at the Department of Pharmacology and Cancer Research UK Cambridge Institute, said: “We thought we’d been given the wrong mice at first. Then we realised that having the BRCA1 mutation seemed to cause the cells in their breast tissue to behave as if the mouse was pregnant.
“The changes we saw happened very early on before any tumours were detected, so we reasoned that markers of these cellular changes could be used to monitor people who we know are at increased risk for breast cancer.”
The team then analysed breast cells from 12 women with a BRCA1 mutation who had undergone a preventative mastectomy.
They found only four had detectable levels of these markers, suggesting the majority of the 12 women were at lower risk of being on the path towards tumour development when they had the surgery.
Larger clinical trials are needed but the hope is to develop a blood test to detect these early changes in BRCA1 breast cells.
Doctors could then screen those at risk and guide them in their decisions over preventative surgery.
Michelle Mitchell, chief executive for Cancer Research UK, said: “The discovery of BRCA mutations gave much needed answers to families with a strong history of breast cancer. However, for women that carry the BRCA mutation that are yet to develop breast cancer, they face an incredibly difficult dilemma.
“This is fascinating research, and we look forward to seeing the next steps, which could mean in the future, doctors could detect if women carrying these mutations have breast cells that are behaving differently.
“This could make a world of difference, as they may not need preventative surgery until later in life, or even at all.”
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