Early Breast Cancer Screening Called Superfluous Despite Family History
GRONINGEN, The Netherlands, July 23 (MedPage Today) -- For a young woman whose sister has had breast cancer, starting immediate intensive surveillance may not be worthwhile, according to epidemiologists here.
Although having a sister with breast cancer increased a woman's likelihood of the same diagnosis, the majority of this risk was concentrated in those ages 50 and older, reported Geertruida H. de Bock, Ph.D., of the Groningen University Medical Center here, and colleagues, online in BMC Cancer.
In their population-based study, a positive family history had a positive predictive value of only 11% for developing breast cancer before age 50 and 1% before age 30.
These findings suggest that the rising demand for intensive screening and BRCA1/2 mutation susceptibility testing among healthy women with a family history of breast cancer will catch few cases before standard screening at a later age would, Dr. de Bock's group said.
"Applying family history related criteria in an unselected population could result in the screening of many women who will not develop breast cancer at an early age," they wrote, at the expense of added anxiety and psychological harm.
Many studies have shown increased risk of breast cancer for relatives of breast cancer patients, with guidelines generally suggesting breast cancer surveillance at age 40 if at least one first-degree relative has been diagnosed with breast cancer before age 40 or 50.
But risk estimates have been based on studies of cancer-prone families and those with BRCA1/2 mutation, which explains just 15% to 20% of familial clustering of breast cancer and less than 5% of overall breast cancer.
To see whether estimates based on these high-risk families would be valuable for prediction of the age of onset of breast cancer in the general population, the researchers analyzed data on sisters of recently diagnosed breast cancer patients unselected for age at diagnosis and family history.
The analysis included 866 women with breast cancer participating in the larger population-based PROSPECT study and their 1,987 sisters.
Sister, mothers, and daughters of these patients had an overall breast cancer rate of 6.8%, which was twice as high as in the general population, similar to what has been seen in prior studies.
About one-quarter of all women in the study had at least one of the following family history risk factors: at least two cases of female breast cancer in first-degree relatives, at least two cases in first or second-degree relatives under the age of 50, at least one case under the age of 40 in a first or second-degree relative, or any case of bilateral breast cancer.
About one-third of women with breast cancer in the study had at least one of these risk factors, as did 40% of the women with breast cancer under age 50, and 60% of the women with an early diagnosis before age 30.
Of the four family history characteristics, bilateral breast cancer conferred the highest risk (hazard ratio 3.47) and having at least one case of female breast cancer before age 40 in the family conferred the lowest risk (HR 2.06).
However, because of the low prevalence of early breast cancer in the study population, the positive predictive values were low for women with one or more and two or more of the family history risk factors. These were, respectively:
- 0.5% and 0.9% for developing breast cancer before age 30.
- 4% and 11% for developing breast cancer before age 50.
- 8% and 13% for breast cancer before age 70.
But the family history factors were more valuable for excluding early breast cancer risk. The negative predictive value ranged from 94% to almost 100%.
"If the model would be used in clinical decision settings, it would be an easy to use method to reassure a large number of women regarding their personal breast cancer risk at an early age and their need to be referred to early screening programs or genetic centers," the researchers concluded.
The study was supported by a grant from the Dutch Cancer Society. The researchers reported no conflicts of interest.
Additional source: BMC CancerSource reference: de Bock GH, et al "A family history of breast cancer will not predict female early onset breast cancer in a population-based setting" BMC Cancer 2008; DOI: 10.1186/1471-2407-8-203.
What breastcancer.org says about this article…
Early Breast Cancer Screening Called Superfluous Despite Family History
The study reviewed here looked at the health histories of more than 800 women diagnosed with breast cancer and almost 2,000 sisters of these women. The research is part of a large study called PROSPECT, which is following the health histories of more than 17,000 women in Holland.
The researchers found that having a first-degree relative (a mother or a sister) diagnosed with breast cancer increases breast cancer risk. But, this higher risk may not be as high as it is thought to be. This is especially true for breast cancer diagnosed before age 50. The results suggest that starting aggressive breast cancer screening before age 50 in women who had a sister diagnosed with breast cancer may not make sense.
About 25% of the women in the study had one or more of the following risk factors:
- at least two cases of breast cancer in first-degree female relatives
- at least two cases of breast cancer in first- or second-degree female relatives younger than 50
- at least one case of breast cancer in a first- or second-degree female relative younger than 40
- a female relative diagnosed with bilateral breast cancer (breast cancer in both breasts)
About 33% of the women in the study diagnosed with breast cancer had a least one of these family health risk factors. The younger a woman was when diagnosed, the more likely she was to have at least one of the risk factors:
- 40% of the women diagnosed with breast cancer younger than 50 had at least one family health risk factor
- 60% of the women diagnosed with breast cancer younger than 30 had at least one family health risk factor
Still, when the researchers looked at a woman's risk of developing breast cancer when she had at least one family health risk factor, the risk was fairly low, especially for developing breast cancer younger than 30.
A woman with one family health risk factor had the following risk:
- 0.5% of developing breast cancer younger than 30
- 4% of developing breast cancer younger than 50
- 8% of developing breast cancer younger than 70
- 0.9% of developing breast cancer younger than 30
- 11% of developing breast cancer younger than 50
- 13% of developing breast cancer younger than 70
Doctors who specialize in determining risk and disease screening make recommendations about who should be screened and when they should be screened. To make these recommendations, the doctors compare screening's benefits to its costs and risks. Costs and risks of screening include the risk of more procedures and tests (and the worry that comes with them) if screening suggests a problem when nothing is wrong.
The benefits of breast cancer screening outweigh the costs and risks for all women older than 50. It's less clear if women younger than 50 get more benefit than risk from aggressive breast cancer screening. In this study, breast cancer risk was higher (and increased more) for breast cancer diagnosed older than 50. So the researchers concluded that starting aggressive breast cancer screening in younger women with one or more family health risk factor may not make sense.
If you have one or more relatives who've been diagnosed with breast cancer, you'll want to do all that you can to reduce your risk of breast cancer. If you've been diagnosed with breast cancer, you want to make sure it's diagnosed as early as possible. You'll also want to make sure that your relatives do all they can to reduce their own risk. No matter how old you are, it's a good idea to work with your doctor to decide on a breast cancer screening approach that makes the most sense for you and your family and your unique situation. Your doctor will probably consider:
- how old people in your family were when diagnosed with breast cancer
- the type and aggressiveness of breast cancer diagnosed in your family
- any family history of an abnormal breast cancer gene
- any family history of ovarian cancer (ovarian cancer increases breast cancer risk)
The breast cancer screening plan you and your doctor develop might include:
- starting screening at an earlier age and screening more than once a year
- adding other screening techniques, such as ultrasound and MRI, to an annual mammogram
- genetic counseling and genetic testing because abnormal BRCA1 and BRCA2 genes are more likely with a strong family history of breast cancer
- screening for ovarian cancer
Visit the Breastcancer.org Lower Your Risk section to learn more about breast cancer risk and what you can do to keep your risk as low as it can be.
