David Brill
Controversy looks set to continue over the benefits of clinical breast examination (CBE) for cancer screening, following the publication of a large population-based study which could raise as many questions as answers.
Results from the Ontario Breast Screening Program show that adding CBE to mammography improves cancer detection rates, but considerably increases the number of false-positive results.
For every 10,000 women screened, the addition of CBE would detect four more cancers but expose 219 women to unnecessary further testing – along with its extra risks, costs and anxiety.
This risk-benefit ratio must be weighed up carefully, and women should be fully informed before consenting to CBE, wrote the researchers, led by Dr. Anna Chiarelli of Cancer Care Ontario, Toronto Canada. [J Natl Cancer Inst 2009 Aug 31; Epub ahead of print]
They screened 290,230 women aged 50 to 69 between 2002 and 2003, and followed them up for 12 months. Of these women, 232,515 received mammography plus CBE at 68 centers (nine regional and 59 affiliated), whereas 57,715 received mammography alone at 34 affiliated centers.
US experts called it “a steep price” for adding CBE to mammography but reserved judgment on how the findings should influence practice, concluding in an editorial that “more answers are needed on the role of CBE in breast cancer screening before definitive recommendations for or against its use can be made.”
“While we wait for those answers, the data presented by Chiarelli et al. suggest that CBE must be done well if it is to be done at all, with the acknowledgment that overall referrals and false-positive results will increase,” wrote Drs. Mary Barton and Joann Elmore, of the Agency for Healthcare Research and Quality, Rockville, and the University of Washington School of Medicine, Seattle, respectively. [J Natl Cancer Inst 2009 Aug 31; Epub ahead of print]
Barton and Elmore also called for the creation of universal standards for CBE, noting that inconsistency in the duration of examinations and the search pattern used can affect the accuracy of the test. They note that the highest-volume centers in the Ontario study also had the highest sensitivities and lowest false-positive rates – an observation which supports their case for standardization.
CBE has been advocated in some quarters since it can detect cancers which are missed by mammography – the gold standard for breast cancer screening. It has yet to be demonstrated conclusively, however, that addition of CBE to screening actually reduces mortality.
The practice is common in the US: one report found that 18 percent of screening centers surveyed performed CBE routinely alongside mammography, while another study found that 65 percent of women reported having CBE in the preceding 2 years. [Open Clin Cancer J 2008;2:32-43; AJR Am J Roentgenol 2005;184:433-8]
Breast cancer was traditionally less common in Asia than the West but rates are rising rapidly. In Singapore, the only Asian country with a national breast cancer screening program, it is now the number one cancer among women. The incidence rose 2.5-fold between 1968 and 2002, according to data from the national cancer registry.
First-line screening in the BreastScreen Singapore program is with mammography alone. CBE is included among possible follow-up tests, along with ultrasound, repeat mammography and biopsy.
Breast cancer has also become the leading cancer among women in Hong Kong – responsible for 21 percent of cancer cases in 2002. A self-referral, opportunistic mammography screening program at the Tung Wah Group of hospitals was shown to improve early detection and prognosis after 46,637 mammograms, with comparable results to Western programs. Screening was well received by the community, and the model has been proposed as a basis for a national program. [Hong Kong Med J 2007;13:106-13c]
Surveys in both Singapore and Hong Kong have shown, however, that public knowledge about breast cancer and screening is low, and myths and misconceptions are common. Only 57 percent of Singaporean women aged 40 and above had gone for a screening mammogram, while 58 percent of Hong Kong women had never even heard of mammographic screening. [Singapore Med J 2009;50:132-8; Breast J 2005;11:52-6]
For every 10,000 women screened, the addition of CBE would detect four more cancers but expose 219 women to unnecessary further testing – along with its extra risks, costs and anxiety.
This risk-benefit ratio must be weighed up carefully, and women should be fully informed before consenting to CBE, wrote the researchers, led by Dr. Anna Chiarelli of Cancer Care Ontario, Toronto Canada. [J Natl Cancer Inst 2009 Aug 31; Epub ahead of print]
They screened 290,230 women aged 50 to 69 between 2002 and 2003, and followed them up for 12 months. Of these women, 232,515 received mammography plus CBE at 68 centers (nine regional and 59 affiliated), whereas 57,715 received mammography alone at 34 affiliated centers.
US experts called it “a steep price” for adding CBE to mammography but reserved judgment on how the findings should influence practice, concluding in an editorial that “more answers are needed on the role of CBE in breast cancer screening before definitive recommendations for or against its use can be made.”
“While we wait for those answers, the data presented by Chiarelli et al. suggest that CBE must be done well if it is to be done at all, with the acknowledgment that overall referrals and false-positive results will increase,” wrote Drs. Mary Barton and Joann Elmore, of the Agency for Healthcare Research and Quality, Rockville, and the University of Washington School of Medicine, Seattle, respectively. [J Natl Cancer Inst 2009 Aug 31; Epub ahead of print]
Barton and Elmore also called for the creation of universal standards for CBE, noting that inconsistency in the duration of examinations and the search pattern used can affect the accuracy of the test. They note that the highest-volume centers in the Ontario study also had the highest sensitivities and lowest false-positive rates – an observation which supports their case for standardization.
CBE has been advocated in some quarters since it can detect cancers which are missed by mammography – the gold standard for breast cancer screening. It has yet to be demonstrated conclusively, however, that addition of CBE to screening actually reduces mortality.
The practice is common in the US: one report found that 18 percent of screening centers surveyed performed CBE routinely alongside mammography, while another study found that 65 percent of women reported having CBE in the preceding 2 years. [Open Clin Cancer J 2008;2:32-43; AJR Am J Roentgenol 2005;184:433-8]
Breast cancer was traditionally less common in Asia than the West but rates are rising rapidly. In Singapore, the only Asian country with a national breast cancer screening program, it is now the number one cancer among women. The incidence rose 2.5-fold between 1968 and 2002, according to data from the national cancer registry.
First-line screening in the BreastScreen Singapore program is with mammography alone. CBE is included among possible follow-up tests, along with ultrasound, repeat mammography and biopsy.
Breast cancer has also become the leading cancer among women in Hong Kong – responsible for 21 percent of cancer cases in 2002. A self-referral, opportunistic mammography screening program at the Tung Wah Group of hospitals was shown to improve early detection and prognosis after 46,637 mammograms, with comparable results to Western programs. Screening was well received by the community, and the model has been proposed as a basis for a national program. [Hong Kong Med J 2007;13:106-13c]
Surveys in both Singapore and Hong Kong have shown, however, that public knowledge about breast cancer and screening is low, and myths and misconceptions are common. Only 57 percent of Singaporean women aged 40 and above had gone for a screening mammogram, while 58 percent of Hong Kong women had never even heard of mammographic screening. [Singapore Med J 2009;50:132-8; Breast J 2005;11:52-6]
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