MONDAY, Sept. 12 (HealthDay News) -- Women with the genetic BRCA
mutations, known to be at higher risk of developing breast and
ovarian cancers, are being diagnosed with those cancers earlier
than previous generations, researchers now report.
''We found with some mathematical modeling about a 7.9-year difference between older and newer [generations]," said Dr. Jennifer Litton, a breast medical oncologist at the University of Texas M.D. Anderson Cancer Center in Houston.
In the study, Litton analyzed the age at diagnosis of two
generations of families in which there were BRCA-related cancers.
Her research included 132 women diagnosed with a BRCA-positive
breast cancer, 106 of whom had a family member of an earlier
generation who had also been diagnosed with a BRCA-related breast
or ovarian cancer.
In the analysis, the median age for the older generation at
diagnosis was 48 (half older, half younger). The median age for the
younger generation was 42. And, in a parametric model, the
estimated change in the expected age at onset for the entire cohort
was 7.9 years, the study showed.
A number of factors could explain the earlier onset, Litton
said. Experts talk about a phenomenon in inherited diseases known
as anticipation. It refers to diseases occurring at younger ages or
with increased severity with each generation. This is due to DNA
instability in which the genes actually evolve and change.
Other factors may also help explain the earlier onset, Litton
added. Among them, better screening and finding cancers at earlier
"It's important to continue to follow this [research] forward and validate it in bigger studies with more women involved," added Litton, whose research is published in the Sept. 12 online edition of the journal Cancer.
For now, the finding validates the recommendation of the
National Comprehensive Cancer Network that screening begin at age
20 to 25 for women at risk of hereditary breast and ovarian cancer
because of the BRCA gene mutations, or five to 10 years earlier
than the youngest age of diagnosis in the family.
Another expert agreed that better screening and earlier
diagnosis, among other factors, may well explain the earlier age at
"This may have nothing to do with genetic anticipation," said Dr. Jeffrey Weitzel, chief of the division of clinical cancer genetics at City of Hope Comprehensive Cancer Center in Duarte, Calif.
The factors explaining the earlier onset in the women with BRCA
mutations could be the same ones that explain trends in the general
population, Weitzel added. "But in high-risk women, it is
Genetic anticipation involves a process in which genes actually
evolve and the underlying structure of the DNA changes, he
Environmental factors and reproductive factors may also play a
role, he said. For instance, a woman whose menstrual periods
started later -- which was often the case with older generations --
is at lower risk of breast cancer than a woman whose period started
at a younger age.
The women in the study reporting the age at diagnosis of an
older family member could also have reported incorrectly, he
The results should inspire younger women with BRCA mutations to
follow screening guidelines, which "have taken this observation
[about earlier diagnosis] into account already," Weitzel said.
Women today, he added, "have access to what your grandmother
didn't have. We have better screening technology."
The risk for women with a BRCA mutation developing breast cancer
is as high as 80 percent, according to the American Cancer
To learn more about breast cancer and BRCA mutations, visit the
American Cancer Society.
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