A new blood test to detect carriers of the BRCA1 or BRCA2 gene mutation for
breast cancer is “faster, more accurate and cheaper” than conventional tests,
claim the researchers at Jerusalem’s Hadassah University Medical Center who
developed the test.
Although not yet on the market, the Hadassah
researchers said it would provide test results in up to six days – instead of a
couple of weeks.
BRCA mutations usually strike at a younger age than
noninherited breast cancer, and also trigger ovarian cancer occur more
frequently in female carriers and prostate cancer in male carriers. According to
an article just published in the journal Cancer Prevention Research, the new
screening test is “95 percent accurate,” even among people who are not
The news has aroused much interest among scientists around the
world as well as the general public.
The research was conducted by Prof.
Tamar Peretz, Yulia Barash and Tamar Zahavi of Hadassah’s Sharett Institute of
Oncology, along with Jasmine Jacob-Hirsch of Sheba Medical Center, Rachel
Levy-Drummer of Bar-Ilan University, Dr. Asher Salmon of Barzilai Medical Center
and Mali Salmon-Divon of Ariel University.
The “simple” test uses white
blood cells separated and cultured in a short time. Afterwards, the cells are
irradiated, and the level of expression of 18 genes are measured. This enables
the identification of carriers at a very high level of accuracy.
said the new test will be an effective alternative for existing ones. The
technology, he added, can “deepen our understanding on the function of cells
harmed by BRCA1 and BRCA2 mutations, and in the future, of additional
In the first stage of the research, the difference in the
expression of genetic profiles in each genome (containing some 30,000 genes) was
examined using expression microarray technology. When the genomes of women with
the mutation and without were compared using “probe sets,” a total of 1,500
genes were found to be expressed differently.
In the second stage, the
list was reduced, using real-time PCR (polymerase chain reaction) technology, to
further shorten the list to 18 genes in which the differences were most
significant. Finally, a validation study of 40 BRCA carriers was conducted
versus a control group, and sensitivity of 95% and specificity of 88% were
found. (Sensitivity measures the proportion of actual positives that are
correctly identified as such, while specificity measures the percentage of
healthy people who are correctly identified as not having the condition.) About
5% of all breast cancers can be attributed to an inherited mutation in one of
two cancer susceptibility genes, but those who have it are much more likely to
develop the cancer than those without the mutation and to contract it in their
fertile years and not in middle and old age, as occurs in non-heritable breast
Asked to comment, BRCA researcher Prof. Ephrat Levy- Lahad – who
is head of medical genetics at the capital’s Shaare Zedek Medical Center – said
Hadassah’s research was “a very interesting preliminary study, but they will
have to show that it holds up with a larger sample of women with mutations and
an even larger range of mutations.”
Levy-Lahad added that “the
specificity is lower than conventional gene sequencing.
The Hadassah team
is competing with the gene sequencing technique, which is the gold standard and
even more accurate. The question is whether their findings will hold up.”