Angelina Jolie's surgery got you worried? Here's what you should know about ovarian cancer risk

Angelina Jolie Pitt has announced she has had her ovaries and fallopian tubes removed to mitigate cancer risk. Photo / AP

Following her 2013 announcement in the op-ed pages of The New York Times that she was having a double mastectomy, US actress Angelina Jolie Pitt has published another piece this week discussing her decision to have her ovaries and fallopian tubes removed to mitigate her high genetic risk of cancer.

Jolie Pitt carries a faulty BRCA1 gene, which predisposes women to developing breast and ovarian cancer. Three women in her family - her mother, aunt and grandmother - were diagnosed with breast or ovarian cancer while still under the age of 60. All three died of their illness.

The publicity surrounding her double mastectomy led to what researchers and the media have dubbed the "Jolie effect". An Australian study published six months after Jolie Pitt's disclosure found referrals to familial cancer centres in Victoria more than doubled, and 64% involved people with a high risk of breast cancer. A similar UK study showed that in the year following her May 2013 announcement, referrals to 12 family history clinics increased over twofold.

But ovarian cancer, as you will see, is very different to breast cancer in that it's very rare. So those of us who work in the field actually hope there's no Jolie effect in this instance because it's likely to cause a lot of worry to women who don't need to be concerned and to divert resources away from those who do.

BRCA and cancer risk

The genes known as BRCA1 and BRCA2 usually help prevent cancers. Everyone has two copies of both but, in some people, one of the copies of either has an error or fault so it doesn't work properly. The result is a high risk of developing breast and ovarian cancer at younger ages than usual.

The lifetime risk of ovarian cancer for a woman with a faulty BRCA1 gene is about 40% to 60%. This risk increases from her late 30s and continues on an upward trajectory with age. Breast cancer risk is also higher for these women and can be up to 80% depending on family history.

The ovarian cancer risk for a BRCA2 fault is not as high as for BRCA1, at between 15% and 25%.

An estimated one in five ovarian cancers occurring at or before the age of 60 is due to a faulty BRCA gene. But only around 1% to 2% of women carry a faulty BRCA gene. Most women without it have only a 1% risk of developing ovarian cancer and a 10% risk of developing breast cancer.

Other gynaecological cancers, such as cervical or uterine cancer, are not known to be associated with the BRCA genes.

Mitigating risk

The surgery Jolie Pitt has just undergone involved the removal of both her ovaries, as well as fallopian tubes. That's because evidence suggests cancer can start in the tubes and travel to the ovaries.

Removing both ovaries and tubes of women with a BRCA fault reduces ovarian cancer risk by 90%. The remaining risk is due to cancer cells that may have already travelled to other sites.

It's important to note that some women with a BRCA fault who have had their ovaries and tubes removed go on to develop what's called primary peritoneal cancer some years later. This can happen even if the tubes looked normal when they were removed. A cancerous cell may have already spread into the peritoneal cavity before surgery, or cancer could have developed there independently. Cells lining the peritoneum can cause a cancer that looks indistinguishable from ovarian cancer.

Removing both ovaries also has the benefit of reducing breast cancer risk by 50%, likely due to the onset of early menopause. A downside of having this surgery is that it prompts the change of life, or menopause, at a younger age. Most women having their ovaries and tubes removed because of a high ovarian cancer risk do so five to ten years before the age of natural menopause, which is around 50-years-old.

Early menopause can result in health issues such as an increased risk of heart disease and osteoporosis, which can be mitigated by hormone replacement therapy. Because of this, a doctor will advise the woman about whether she should use hormone replacement, which may also help delay or reduce the onset of menopausal symptoms, such as hot flushes, premature ageing of tissues, vaginal thinning (causing sexual discomfort) and decreased libido.

One way to reduce the risk of ovarian cancer is by using the oral contraceptive pill, which can halve your risk with five years of use.

Don't panic

Of course, it would be far better to have a reliable screening test to detect ovarian cancer at an early, curable stage before women develop symptoms. Sadly, neither of the two tools we have now can do this.

The CA-125 blood test is no longer recommended because it detects cancer at a point when it can no longer be cured. And internal pelvic ultrasounds, which look for abnormalities in the ovary, are not sensitive enough to pick up early changes. Both help diagnose established cancers that would usually be picked up within three months anyway because of symptoms.

Jolie said she had planned to have her ovaries and tubes removed ten years before the youngest woman in her family was diagnosed, but this is not a universal rule for women who carry a BRCA fault. Usually, we use the more blanket approach of surgery around 40 years of age, which is when most women have had their children. Earlier surgery would further increase the risk of problems associated with early menopause.

Women who have had ovarian cancer and are concerned about others in their family should ask their doctor whether the BRCA genes might have played a role in their illness. Those who have a close relative, such as a mother or a sister, who was diagnosed with ovarian cancer while younger than 70 should contact Ovarian Cancer Action (UK), Ovarian Cancer Australia, Ovarian Cancer National Alliance (US) or consult their doctor.

Genetic counselling and testing through a familial cancer centre may be recommended for some. For women who have the faulty BRCA genes, there's ongoing peer and professional support.

Women who don't have a close relative with ovarian cancer do not need to seek advice based on the surgery Jolie has just undergone.

Jolie Pitt's op-ed about her double mastectomy had a positive impact as it galvanised many women to have their risk of breast cancer assessed, including some who needed to be tested for the BRCA mutation. This latest announcement should not have the same effect as far fewer women are at high risk of ovarian cancer.

This article was co-authored by Maira Kentwell, senior genetic counsellor and manager of the Department of Genetic Medicine and Familial Cancer Centre, The Royal Melbourne Hospital.

Clare Scott is a Medical Oncologist and Laboratory Head at Walter and Eliza Hall Institute

This article was originally published on The Conversation.