BRCA Gene Does Not Increase Breast Cancer Death, New Study

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Main Category: Breast Cancer
Also Included In: Genetics
Article Date: 12 Jul 2007 - 0:00 PDT

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A new study shows that rates of death due to breast cancer among Israeli Ashkenazi women who carried either a BRCA1 or BRCA2 gene variant were no different to the rates for women who were non carriers.

The study is published in the New England Journal of Medicine (NEJM) and was the work of Dr Gad Rennert, of Clalit Health Services, National Cancer Control Center and Department of Community Medicine and Epidemiology, Carmel Medical Center, Haifa, Israel and colleagues also in Israel and Canada.

According to the National Cancer Institute, between 5 and 10 per cent of breast cancers are due to inherited gene mutations. And the lifetime risk of developing breast cancer is between 3 and 7 times higher for carriers of BRCA1 and BRCA2 mutations than non carriers.

The researchers said that previous studies have suggested that women with breast cancer and a BRCA1 mutation have a poor prognosis.

Rennert told the WebMD health website that:

"We know that women with BRCA1 and BRCA2 mutations tend to show up with bad prognostic factors: characteristics that suggest they are at very high risk."

"But our results suggest the outcomes among these women are often much better than would be expected," he added.

Information from the Chicago Center for Jewish Genetic Disorders shows that ethnic specific mutations of BRCA1 and BRCA2 have been found in a number of populations, including Dutch and Icelandic, and a higher incidence of three mutations of BRCA1 and BRCA2 has been found in the Ashkenazi Jewish population.

The incidence of all three BRCA1 and BRCA2 mutations is calculated to be around 2.5 per cent in the Ashkenazi Jewish population, compared to less than 1 per cent in the general population.

Rennert and colleagues decided to conduct a retrospective population study to look at the influence of BRCA1 or BRCA2 mutations on the prognosis outcomes for breast cancer in Jewish Ashkenazi women in Israel because this was the most likely source of a large enough population of carriers and non carriers. Also Israel has a National Cancer Registry.

They collected data on all incident cases of invasive breast cancers recorded in the Israel National Cancer Registry that were diagnosed between the start of 1987 and the end of 1988.

They also took DNA from tumour samples to look for the three founder mutations in BRCA1 and BRCA2 and reviewed the associated pathological and clinical records.

The results showed they were able to get DNA from 71 per cent of the 2,514 women in the study, and medical records for 86 per cent.

They found that 10 per cent of the sampled participants carried either a BRCA1 or a BRCA2 mutation.

When they examined the hazard ratio (HR) for death, they found no significant difference in the risk of death between mutation carriers and non carriers.

They concluded that:

"Breast cancer-specific rates of death among Israeli women are similar for carriers of a BRCA founder mutation and noncarriers."

According to the National Cancer Institute, in the US, 1 in 50 women will develop breast cancer by the age of 50 and this goes up to 1 in 10 by the age of 80. Second to skin cancer, breast cancer is the most commonly diagnosed cancer in women, of which there are 180,000 new cases a year and 45,000 deaths.

Breast cancer occurs more in white women than African American or Asian women. It also occurs in men, which make up fewer than 1 per cent of cases.

"Clinical Outcomes of Breast Cancer in Carriers of BRCA1 and BRCA2 Mutations."
Rennert, Gad, Bisland-Naggan, Shantih, Barnett-Griness, Ofra, Bar-Joseph, Naomi, Zhang, Shiyu, Rennert, Hedy S., Narod, Steven A.
N Engl J Med 2007 357: 115-123
Volume 357:115-123; July 12, 2007; Number 2

Click here for Abstract.

Click here for more information on "Ashkenazi Jews and BRCA1 and BRCA2" from the Chicago Center for Jewish Genetic Disorders.

Written by: Catharine Paddock
Writer: Medical News Today
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today