As a Hollywood star with global appeal, Angelina Jolie's decision to publicise her preventative double mastectomy to reduce her chances of developing breast cancer has given support to women in a similar situation, say campaigners.
Her article in the New York Times has generated worldwide headlines about the risks of developing breast cancer comparable perhaps only to the publicity after Kylie Minogue revealed in 2005 that she had been diagnosed with the disease. The Australian star was given the all-clear the following year after surgery and chemotherapy.
Jolie wrote in the article entitled My Medical Choice that she carries a "faulty" BRCA1 gene, which sharply increases her risk of developing breast cancer and ovarian cancer.
Doctors estimated that she had an 87 per cent risk of breast cancer and a 50% risk of ovarian cancer, although the risk is different in the case of each woman, she said.
Her decision to go ahead with the mastectomy operation was "not easy" but she was "very happy" she had done so, as her chances of developing breast cancer following surgery have now dropped from 87 per cent to under 5 per cent.
Katherine Woods, research information manager at Breast Cancer Campaign, said about 50,000 cases of breast cancer in women are diagnosed every year in the UK. Around one in 20 of these, or 2,500, are thought to have been caused by inheriting a faulty BRCA gene.
"The BRCA gene is really important in repairing damage to DNA. If that gene becomes damaged itself then the body is compromised in its ability to fix damage that occurs to DNA. In that case, that makes cancer a lot more likely to develop," she said.
She said the risk of developing breast cancer if there is a BRCA gene fault varies widely. "It really depends on the exact mutation that a woman has," she said.
For a faulty BRCA 1 gene the average risk is 55 per cent of developing breast cancer for women by the age of 70 years old. For BRCA 2 this average falls to 47 per cent, she said.
"It may not be helpful to talk about averages because there are such ranges," she said. "The range that we know about can be anything from 30 per cent up to 90 per cent."
She said family history and the closeness of relatives with the disease was a factor in deciding whether to refer a woman for possible genetic testing.
"It is about how many close relatives have developed breast cancer, whether it is a sister or a mother or a daughter who have developed breast cancer," she said.
"It is the number of these close relatives who have developed breast cancer and also the age at which they have developed it.
"Breast cancer tends to happen at a later age on the whole. If people in the family are getting it at a younger age then that may be a sign that genetics are at play."
She said women who were concerned should contact their GP. A GP would make a calculation of risks from family history before making a decision on whether to refer to a genetic counsellor.
"A woman would be talked through all that information and given all the facts that she needs to make a decision about whether she wants genetic testing," she said.