The age at which breast cancer is diagnosed in families with an abnormal breast cancer gene (BRCA1 or BRCA2) was nearly 8 years earlier in the younger generation compared to the older generation according to a new study. The results were presented at the 2009 ASCO Breast Cancer Symposium.
Women with an abnormal BRCA1 or BRCA2 gene have up to a 60% risk of developing breast cancer by age 70. Their risk of ovarian cancer also is higher than average. Abnormal BRCA1 and BRCA2 genes are found in 5% to 10% of all breast cancer cases in the United States.
In this study, researchers identified 106 families in which close relatives from successive generations had an abnormal BRCA1 or BRCA2 gene and were diagnosed with a BRCA-related cancer (mostly breast cancer). More than 300 women from these families had been diagnosed with cancer.
The researchers found that breast cancer was diagnosed earlier in members of the younger generation compared to members of the older generation, no matter when the women were born. For example, some younger generation women were born in the 1950s and their average age at diagnosis was 43.5. Their older generation relatives were diagnosed at an average age of 50 -- a difference of 6.5 years. Younger generation women born in the 1970s (the youngest women in this study) were diagnosed at an average age of 31, compared to an average age of 44.5 for their older generation relatives -- a difference of 12.5 years.
The researchers aren't sure what's causing this trend of younger diagnosis. Two scenarios are likely contributing to the trend:
Each year, more people learn about the link between breast cancer risk and abnormal BRCA1 and BRCA2 genes. At the same time, doctors promote more aggressive breast cancer screening in anyone with a known abnormal breast cancer gene. Both of which may be causing more breast cancers to be found earlier. In other words, breast cancer may not be developing earlier in younger generation women, but it's being diagnosed earlier.
Unfavorable lifestyle choices and environmental factors (for example, eating an unhealthy diet or smoking) can increase breast cancer risk and may be causing breast cancer to develop earlier in younger generation women with an abnormal breast cancer gene.
The American Cancer society currently recommends that women with an abnormal breast cancer gene start breast cancer screening at age 25 (compared to age 40 for women with an average risk of breast cancer). Since women with an abnormal BRCA1 or BRCA2 gene are being diagnosed at younger ages, the researchers wonder if screening at an earlier age should be considered in the future.
If you or a close family relative has an abnormal breast cancer gene, it's important that you work closely with your doctor to get the testing and regular screening that's best for your situation and your personal risk. You also should make diet and lifestyle choices to help keep your breast cancer risk as low as possible. Your younger relatives (daughters, granddaughters, nieces) should do the same things.
You can learn more about BRCA1 and BRCA2 gene abnormalities in the Breastcancer.org Breast Cancer Risk Factors: Genetics page.
SAN FRANCISCO (MedPage Today) -- The age at which breast cancer is diagnosed in families that carry harmful BRCA mutations appears to be getting younger in succeeding generations, researchers found.
The median age of breast cancer onset in BRCA1 or 2 carriers was six years earlier than for their mothers and aunts, Jennifer Litton, MD, of the M.D. Anderson Cancer Center in Houston, and colleagues reported here at the ASCO Breast Cancer Symposium.
This relationship wasn't limited to the youngest generation of women in a family, who would presumably have access to genetic testing and modern intensive screening programs, Litton's group found.
Rather, second-generation cancer cases in these families were diagnosed at younger ages regardless if they were born in the 1950s or 1970s.
One reason for the shift in age at diagnosis could be that guidelines for early screening and more sensitive imaging technologies have pushed back the age such that at-risk women may be diagnosed with smaller, earlier stage tumors, Litton speculated.
"People are certainly more aware, particularly women with a strong family history," she said.
However, changing lifestyle and environmental factors, such as obesity and later age at childbirth, may be interacting with the already high hereditary risk as well.
"We just don't know," Litton added.
The American Cancer Society recommends that women with known BRCA mutations and those whose mothers or aunts from either side of the family have the mutation be screened starting at age 25.
However, the new findings suggest that oncologists may start seeing the disease even earlier in future generations, a shift that might need to be anticipated in treatment guidelines and in counseling patients, Litton said.
Litton said she often sees women with a strong family history of breast cancer, but started noticing that they -- and particularly those who tested positive for risk-associated mutations -- were appearing at a younger and younger age.
So she and colleagues went through records of all the women they had seen at M.D. Anderson who had been diagnosed with a BRCA1 or 2 mutation to see whether this suspicion was a real phenomenon.
Women seen at the genetic clinic there complete a detailed questionnaire listing all family members and any breast or ovarian cancers -- the cancer types linked to the mutations -- with the age at diagnosis for each affected relative.
Through these pedigrees, the researchers were able to identify 106 families with a confirmed BRCA-related malignancy in two subsequent generations, for a total of 303 affected individuals.
These mother/daughter and aunt/niece pairs revealed that the younger generation was diagnosed at age 42 on average, compared with onset at 48 in the older generation, a significant difference of six years between pairs (P<0.001).
When all affected individuals in each generation were accounted for, the difference was even greater: a 7.9-year earlier onset in later generations (average 36.77 versus 48.98, P<0.0001).
Too few second-generation women had been born in the 1930s to analyze a trend, but second-generation women born in every subsequent decade at least tended to have an earlier age at breast cancer diagnosis than their affected relatives:
The researchers cautioned that recall bias related to age at diagnosis may have limited the results, along with inability to test whether all breast and ovarian cancers were correctly attributed to BRCA mutations in the older generations.
The study was funded by the Nellie B. Connally Breast Cancer Research Fund. The researchers reported no conflicts of interest.
Primary source: ASCO Breast Cancer Symposium Source reference: Litton JK, et al "Earlier age of onset of BRCA mutation-related cancers in subsequent generations" ASCO Breast 2009; Abstract 7.
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