A new drug for genetic breast cancer could help thousands of women with hereditary forms of the disease, the first tests on patients suggest.

A study involving 54 women with advanced genetic breast cancer found that the drug olaparib could stop the growth of tumours, and shrink them in more than 40 per cent of cases.

In one case, a woman’s tumour disappeared completely after treatment with the drug, according to results to be presented at a science conference today.

About 5 per cent of the 46,000 cases of breast cancer in Britain each year are caused by defects on the BRCA-1 and BRCA-2 genes, which put women at much higher risk of developing aggressive cancers of the breast or ovaries.

Many women who test positive for the mutations have their breasts removed as a precaution, as they have an 80 per cent risk of developing breast cancer in their lifetime.

Olaparib, made by AstraZeneca , is the first of a new class of drugs specifically designed to treat BRCA-related cancers to be tested on patients. If further tests are successful, they could be used at an early stage to treat or prevent disease occurring within affected families, scientists say.

Pharmaceutical companies are also due to present targeted therapies for cancers of the lung, stomach and ovaries this week at the American Society of Clinical Oncology conference in Orlando, Florida, the world’s largest gathering of cancer scientists.

Andrew Tutt, director of the Breakthrough Breast Cancer Research Unit at King’s College London, who led the trial, said that the results for olaparib were “very promising”.

“We are hopeful that olaparib could provide a targeted treatment for women with BRCA-related breast cancer,” he said. “Some women also develop breast cancer before they know they are carrying the gene, or see it recur if they have been diagnosed previously.”

Charlotte Sword, 40, has had breast cancer diagnosed twice, because of the potentially deadly mutation to the BRCA-1 gene which runs in her family. Her younger sister Audrey has suffered it three times. Both women have had double mastectomies and their ovaries removed.

“Breast cancer has left a horrific mark on our family due to a mutation being passed down the paternal line”, Mrs Sword said yesterday. “I have three nieces who could benefit from this treatment, and could be spared the dreadful illness and side-effects of treatment that my sister and I had to go through.”

Olaparib works by blocking a protein that makes cancer cells which have a BRCA fault unable to repair their own DNNA. This causes the cancer cell to die and means that the tumour should either stop growing or get smaller.

Because the drug works in a targeted way, it kills cancer cells while leaving healthy cells alone in a way that chemotherapy does not, which could help to reduce the punishing side-effects of cancer treatment.

In the study carried out at hospitals in Britain, Europe, the US and Australia, 27 patients took 100mg oral doses of olaparib while another 27 took 400mg doses. More than 40 per cent of tumours in the higher dose group reduced significantly in size, while all tumours were prevented from progressing for an average of six months.

The Times reported this year that the London community of Ashkenazi Jews is being offered screening for BRCA genes that raise risks of breast, ovarian and prostate cancers. Ashkenazi have a high incidence of BRCA-related breast cancer.

The NHS currently offers BRCA testing, but only for women whose relatives have had cancer because of the mutations. But up to 50 per cent of people with the faulty genes do not have a family history of the diseases, largely because the gene can be carried by men.

Dr Tutt said that orlaparib may also have potential as an early-stage or preventative treatment. He added: “It is important to remember this drug is at a very early stage of development.” Herbie Newell, Cancer Research UK scientist at the Northern Research Institute, Newcastle University, said he was “extremely encouraged” by the study’s results.

He said: “Olaparib is one of a family of targeted therapies currently in clinical trials and Cancer Research UK expect that this new class of anti-cancer treatments will make a significant impact in the fight against cancer."

In the family

8% Proportion of cases of breast cancer in women thought to be triggered by genetic factors, although many of the exact causes remain a mystery

2,000 Number of breast cancer cases a year (5 per cent of the total) known to be caused by changes in either the BRCA-1 or BRCA-2 genes that were the first to be associated with a much higher risk of developing breast cancer

1 in 800 Proportion of women in whom a faulty BRCA-1 gene is present. One in 500 carries a faulty copy of the BRCA-2 gene

50-80% Chances of a woman with these genes of getting breast cancer in their lifetime, up to seven times higher than those who do not carry the mutations. They also have a 60 per cent increased risk of ovarian cancer

Sources: Cancer Research UK; Times database

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