Up to one in five women with breast cancer could benefit from a type of treatment currently only given to patients with a rare form of the disease caused by gene mutations, scientists have said.
Drugs designed to treat less common cases of breast cancer driven by faults in tumour-suppressing BRCA genes may also help women with more common forms of the disease, according to a new study.
Researchers from the Wellcome Trust Sanger Institute found some 8,000 more patients may respond to the drugs than are receiving them at present.
Around one to five per cent of the the 55,000 women diagnosed with breast cancer in the UK each year are thought to have BRCA-driven disease.
Actor Angelina Jolie underwent a double mastectomy when she discovered she had inherited a faulty gene known as BRCA1, which meant she had an 87 per cent risk of developing breast cancer.
The scientists said thousands of more common forms of breast cancers were biochemically similar to these rarer cases involving BRCA1 and BRCA2 gene mutations.
“Our study shows that there are many more people who have cancers that look like they have the same signatures and same weakness as patients with faulty BRCA1 and BRCA2 genes,” said lead researcher Dr Serena Nik-Zainal.
13 ways to help prevent cancer
13 ways to help prevent cancer
Stopping smoking. This notoriously difficult habit to break sees tar build-up in the lungs and DNA alteration and causes 15,558 cancer deaths a year
Avoiding the sun, and the melanoma that comes with overexposure to harmful UV rays, could help conscientious shade-lovers dodge being one of the 7,220 people who die from it
A diet that is low in red meat can help to prevent bowel cancer, according to the research - with 30 grams a day recommended for men, and 25 a day recommended for women
Foods high in fibre, meanwhile, can further make for healthier bowels. Processed foods in developed countries appear to be causing higher rates of colon cancer than diets in continents such as Africa, which have high bean and pulse intakes
Two servings of fruit and three servings of vegetables a day were given as the magic number for good diet in the research. Overall, diet causes only slightly fewer cancer deaths than sun exposure in Australia, at 7,000 a year
Obesity and being overweight, linked to poor diet and lack of exercise, causes 3,917 deaths by cancer a year on its own
Dying of a cancer caused by infection also comes in highly, linked to 3,421 cancer deaths a year. Infections such as human papilloma virus - which can cause cervical cancer in women - and hepatitis - can be prevented by vaccinations and having regular check-ups
Cutting back on drinks could reduce the risk of cancers caused by alcohol - such as liver cancer, bowel cancer, breast cancer and mouth cancer - that are leading to 3,208 deaths a year
2014 Getty Images
Sitting around and not getting the heart pumping - less than one hour's exercise a day - is directly leading to about 1,800 people having lower immune functions and higher hormone levels, among other factors, that cause cancers
2011 Getty Images
Hormone replacement therapy, which is used to relieve symptoms of the menopause in women, caused 539 deaths from (mainly breast) cancer in Australia last year. It did, however, prevent 52 cases of colorectal cancers
2003 Getty Images
Insufficient breastfeeding, bizarrely, makes the top 10. Breastfeeding for 12 months could prevent 235 cancer cases a year, said the research
Oral contraceptives, like the Pill, caused about 105 breast cancers and 52 cervical cancers - but it also prevented about 1,440 ovarian and uterine (womb) cases of cancer last year
2006 Getty Images
Taking aspirin also prevented 232 cases in the Queensland research of colorectal and oesophagal cancers - but as it can also cause strokes, is not yet recommended as a formal treatment against the risk of cancer
Dr Nik-Zainal said these women may respond to a class of drugs known as PARP inhibitors that are are specifically designed to target tumours with the defective genes. “We should explore if they could also benefit from PARP inhibitors,” she said.
The team, whose results are published in the journal Nature Medicine, analysed DNA from breast cancer tissue samples taken from 560 patients.
A piece of computer software called HRDetect was used to identify genetic code “fingerprints” revealing biochemical pathways like those associated with mutant BRCA1 and 2 genes.
Of the total group of patients, 22 had previously diagnosed BRCA 1 and 2 mutations. Another 55 had unexpected BRCA mutations, including some very unusual ones that were not inherited.
A further 47 had BRCA genes with no recognised mutations, yet in these patients the repair mechanisms controlled by the genes were still faulty.
“It's possible there are other ways of turning off BRCA 1 and 2 that we don't understand, perhaps involving other genes,” said Dr Nik-Zainal.
She added: “PARP inhibitors are important for quality of life because they specifically target cancer cells and so are well tolerated.
“I feel so strongly about the fact that one in five women might benefit from these drugs. A lot of people who could be getting these treatments are not being offered them.”
But she pointed out that a lot more evidence had to be collected before guidelines on the use of PARP inhibitors could be changed.
Baroness Delyth Morgan, chief executive of the charity Breast Cancer Now, said she hoped the findings could lead to a “watershed moment” in the treatment of the disease.
“PARP inhibitors are a very promising treatment on the horizon and the suggestion that more patients may be able to benefit from them is greatly exciting,” she said.
“Crucially, this study is an early but encouraging step towards being able to offer women treatments targeted to the genetic make-up of their breast cancer.
“The discovery that many women may have tumours genetically similar to patients with faulty BRCA genes, without them actually having a BRCA mutation, is somewhat of a revelation.”
Additional reporting from Press AssociationReuse content