A voice for women's health

The Breast Cancer Genes

May 2013

On the 14th of May 2013 Angelina Jolie’s revelation that she carried the BRCA1 breast cancer gene and had had a preventative double mastectomy made world headlines and the fear of breast cancer went through the roof. Women’s support groups, health centres and health agencies were deluged with calls from fearful women who wondered if they might have either of the BRCA1 and BRCA2 genes that are associated with a high risk of breast and ovarian cancer.

In the aftermath of the publication of Angelina Jolie’s story in the New York Times1, risk percentages for breast cancer were exaggerated and talked about as though they were death sentences. Her 87% risk of breast cancer became 90% which according to Professor Geoff Lindeman, head of the RMH Familial Cancer Centre, was “the upper end of risk when the gene was first discovered.”2

Only about 5% of all breast cancers are hereditary, and not all of them will involve the BRCA1 or BRCA2 gene. The risk of cancer for women with the breast cancer gene is somewhere between 40 – 65% with the risks for women with the BRCA1 gene being higher than for those with the BRCA2 gene. In the midst of the panic that was generated by Angelina Jolie’s story it is important to keep in mind that having either of these genes does not mean that a woman will develop either breast cancer or ovarian cancer.2

The BRCA genes play an important role in repairing the breaks or mutations in the DNA in our cells. But just as the body has a number of pathways that lead to cancer, it also has several pathways to repair DNA. The majority of women who are diagnosed with breast cancer have completely intact BRCA genes so there is obviously more to this than genomics.

It is also worth noting that men who inherit either of these genes may be at increased risk of prostate cancer as well as breast cancer – “breast cancer in men carrying BRCA2 has also been described in the medical literature.”2

 

Genetic Testing

The demand for genetic testing is probably also going through the roof as a result of the New York Times article. Yet, Professor Lindeman urges caution, and advises against routine genetic testing. “Testing is offered to people who have developed breast or ovarian cancer where there are features that might suggest a mutation is present,” he says.

The test is also extremely expensive as Myriad Genetics, a Utah-based company, patented the test and is currently the sole producer of it. In fact Myriad claims to own the rights to any test associated with the BRCA1 and BRCA2 genes and it has ruthlessly enforced that right, even though their test is inferior to one that Yale University was willing to provide at a much lower cost. The US Supreme Court has recently begun deliberations on the latest of a series of legal challenges to the granting of the patent that has been going on for over three years.

Referring to the fact that her wealth meant she has choices that other women do not have, Angelina Jolie observed that, “the cost of testing for BRCA1 and BRCA2, at more than $3,000 in the United States, remains an obstacle for many women.”

 

Overdiagnosis

Angelina Jolie’s situation also differs in other respects from those of the average woman. She is a woman at high risk compared to the vast majority of women who take part in breast screening programmes and after a biopsy receive a diagnosis of breast cancer. It is now known that about a quarter of cancers detected are so small or slow-growing that they will never metastasise or cause any health problems.

Other women are told they have ductal carcinoma in situ (DCIS), a kind of pre-cancer in which abnormal cells are found in the milk-producing ducts. Before screening programmes were introduced, DCIS was rare. Now they account for around 25% of new breast-cancer cases, and preventative double mastectomies among women in this group have risen by 188% since the late 1990s.3 This despite the fact that between 50 – 80% of DCIS cases will not develop into invasive cancer. In the USA the impact of such diagnoses turns thousands of healthy women into “cancer survivors” every year, and fuels the culture of fear, adding to women’s already exaggerated sense of risk of getting breast cancer.4

The results of a large study of breast cancer diagnoses over the past 30 years appeared in the New England Journal of Medicine at the end of 2012. It found that despite substantial increases in the number of cases of early-stage breast cancer detecting, screening mammography had only marginally reduced the rate at which women present with advanced cancer and that there is substantial overdiagnosis accounting for nearly a third of all newly diagnosed breast cancers. The study suggested that more than one million women may have been unnecessarily diagnosed and treated.5

 

Preventative Options

Professor Lindeman suggested that there were a number of preventative options such as “close monitoring which includes MRI scans and mammograms starting at a suitable age,” and breast cancer prevention drugs such as Tamoxifen. As for mastectomy followed by breast reconstruction, he estimated that on average about 20% of women in Australia found to be carrying the BRCA1 and BRCA2 genes opt for this option.2
 

Mastectomy

As the breast cancer survivor quoted earlier put it, “having a mastectomy … is a huge ordeal. And reconstruction, while it can look great, will never have sensation. Not ever again. So before removing her breasts, a woman … should understand her personal risk of future disease. She should know that many breast cancers are survivable, and that the disease is not necessarily a death sentence… Knowledge is power: before you remove a breast, be sure you are fully informed”3
 

References
  1. Angelina Jolie: My Medical Choice, New York Times, May 14, 2013
  2. The Conversation: Angelina Jolie has had a double mastectomy, so what is BRCA1? May 14, 2013
  3. Peggy Orenstein: Reacting to Angelina Jolie’s Breast Cancer News. The 6th Floor, Just another nytimes.com Blogs weblog, May 15, 2013
  4. Peggy Orenstein: Our Feel-Good War on Breast Cancer. New York Times, April 25, 2013
  5. Archie Bleyer and H. Gilbert Welch: Effect of Three Decades of Screening Mammography on Breast-Cancer Incidence. November 22, 2012, N Engl J Med 2012; 367:1998-2005
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