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BACKGROUND: Annual screening mammography is universally accepted as the standard of care in the United States for woman 50 years and older. Although evidence supports screening as effective in reducing breast cancer mortality, it is not known whether mammography plus a clinical breast examination (CBE) is more effective at reducing cancer mortality than a thorough CBE alone.
POPULATION STUDIED: A total of 39,459 Canadian women 50 to 59 years were recruited through general publicity, mailings, and physician referral. These women had not received a mammogram in the previous year and did not have a history of breast cancer.
STUDY DESIGN AND VALIDITY: The women were randomized to receive either 5 annual CBEs with mammography or a CBE alone annually for 5 years. Well-trained nurses using a visual inspection component and palpation in a radial pattern performed most of the breast examinations. Physicians performed the others. The examinations were very thorough and took approximately 10 minutes. Patients were also taught breast self-examination. Two-view mammograms were used and independently reviewed. Patients with abnormal findings were referred to the Canadian National Breast Screening Study (CNBSS) clinic for further evaluation by a surgeon. Breast cancers were identified through the CNBSS centers and the National Cancer Registry during the 13-year follow-up. The cause of death was identified through the participant’s family members, physicians, and the Canadian Mortality Data Base. Overall the study appeared valid. The 2 randomized groups seemed equal for breast cancer risk factors and other demographics. There was excellent follow-up and good compliance within each group. Randomization was not concealed. Previous scrutiny of this study centered on a change in mammography technique during the screening. Further analysis showed high sensitivity and expected cancer detection rates despite this change. The article does not mention what types of screening the participants underwent after the initial 5-year study period. This could potentially have an effect on the mortality numbers, if women decided to stop their screening after the study period ended. This study did not address differences in quality of life, such as discomfort from mammograms and additional procedures from false-positive screenings.
OUTCOMES MEASURED: Breast cancer mortality was the primary outcome. The tumor size and number of lymph node–positive cancers were also reported.
RESULTS: Only 54 of the original participants were excluded from the analysis. At the 13-year follow-up there were 107 breast cancer deaths in the combined mammography plus CBE group and 105 deaths in the CBE-only group (rate ratio=1.02; 95% confidence interval, 0.78-1.33). A total of 622 invasive and 71 in situ cancers were found in the combined group and 610 invasive and 16 in situ cancers were identified in the CBE-only group. Mammography was able to detect a cancer 2.1 years earlier than CBE alone. However, this lead time did not appear to improve survival. Overall, the tumors identified by mammography were smaller. There was no significant difference between the 2 groups in the number of lymph node–positive cancers detected by the end of the study. As expected, there were approximately 3 times as many biopsies and more diagnostic tests performed in the mammogram group.
This study found that in women 50 to 59 years the addition of annual screening mammograms to a very thorough clinical breast examination does not reduce breast cancer mortality over a 13-year follow-up. Although cancer detection rates were slightly higher in the mammogram group, there was also a 3-fold increase in the number of biopsies. This study might be reassuring in those parts of the world where mammography is not readily accessible. However, it is unlikely that these results will change practice in the current United States health care environment. In patients who refuse mammography, a thorough CBE may be as effective.
BACKGROUND: Annual screening mammography is universally accepted as the standard of care in the United States for woman 50 years and older. Although evidence supports screening as effective in reducing breast cancer mortality, it is not known whether mammography plus a clinical breast examination (CBE) is more effective at reducing cancer mortality than a thorough CBE alone.
POPULATION STUDIED: A total of 39,459 Canadian women 50 to 59 years were recruited through general publicity, mailings, and physician referral. These women had not received a mammogram in the previous year and did not have a history of breast cancer.
STUDY DESIGN AND VALIDITY: The women were randomized to receive either 5 annual CBEs with mammography or a CBE alone annually for 5 years. Well-trained nurses using a visual inspection component and palpation in a radial pattern performed most of the breast examinations. Physicians performed the others. The examinations were very thorough and took approximately 10 minutes. Patients were also taught breast self-examination. Two-view mammograms were used and independently reviewed. Patients with abnormal findings were referred to the Canadian National Breast Screening Study (CNBSS) clinic for further evaluation by a surgeon. Breast cancers were identified through the CNBSS centers and the National Cancer Registry during the 13-year follow-up. The cause of death was identified through the participant’s family members, physicians, and the Canadian Mortality Data Base. Overall the study appeared valid. The 2 randomized groups seemed equal for breast cancer risk factors and other demographics. There was excellent follow-up and good compliance within each group. Randomization was not concealed. Previous scrutiny of this study centered on a change in mammography technique during the screening. Further analysis showed high sensitivity and expected cancer detection rates despite this change. The article does not mention what types of screening the participants underwent after the initial 5-year study period. This could potentially have an effect on the mortality numbers, if women decided to stop their screening after the study period ended. This study did not address differences in quality of life, such as discomfort from mammograms and additional procedures from false-positive screenings.
OUTCOMES MEASURED: Breast cancer mortality was the primary outcome. The tumor size and number of lymph node–positive cancers were also reported.
RESULTS: Only 54 of the original participants were excluded from the analysis. At the 13-year follow-up there were 107 breast cancer deaths in the combined mammography plus CBE group and 105 deaths in the CBE-only group (rate ratio=1.02; 95% confidence interval, 0.78-1.33). A total of 622 invasive and 71 in situ cancers were found in the combined group and 610 invasive and 16 in situ cancers were identified in the CBE-only group. Mammography was able to detect a cancer 2.1 years earlier than CBE alone. However, this lead time did not appear to improve survival. Overall, the tumors identified by mammography were smaller. There was no significant difference between the 2 groups in the number of lymph node–positive cancers detected by the end of the study. As expected, there were approximately 3 times as many biopsies and more diagnostic tests performed in the mammogram group.
This study found that in women 50 to 59 years the addition of annual screening mammograms to a very thorough clinical breast examination does not reduce breast cancer mortality over a 13-year follow-up. Although cancer detection rates were slightly higher in the mammogram group, there was also a 3-fold increase in the number of biopsies. This study might be reassuring in those parts of the world where mammography is not readily accessible. However, it is unlikely that these results will change practice in the current United States health care environment. In patients who refuse mammography, a thorough CBE may be as effective.
BACKGROUND: Annual screening mammography is universally accepted as the standard of care in the United States for woman 50 years and older. Although evidence supports screening as effective in reducing breast cancer mortality, it is not known whether mammography plus a clinical breast examination (CBE) is more effective at reducing cancer mortality than a thorough CBE alone.
POPULATION STUDIED: A total of 39,459 Canadian women 50 to 59 years were recruited through general publicity, mailings, and physician referral. These women had not received a mammogram in the previous year and did not have a history of breast cancer.
STUDY DESIGN AND VALIDITY: The women were randomized to receive either 5 annual CBEs with mammography or a CBE alone annually for 5 years. Well-trained nurses using a visual inspection component and palpation in a radial pattern performed most of the breast examinations. Physicians performed the others. The examinations were very thorough and took approximately 10 minutes. Patients were also taught breast self-examination. Two-view mammograms were used and independently reviewed. Patients with abnormal findings were referred to the Canadian National Breast Screening Study (CNBSS) clinic for further evaluation by a surgeon. Breast cancers were identified through the CNBSS centers and the National Cancer Registry during the 13-year follow-up. The cause of death was identified through the participant’s family members, physicians, and the Canadian Mortality Data Base. Overall the study appeared valid. The 2 randomized groups seemed equal for breast cancer risk factors and other demographics. There was excellent follow-up and good compliance within each group. Randomization was not concealed. Previous scrutiny of this study centered on a change in mammography technique during the screening. Further analysis showed high sensitivity and expected cancer detection rates despite this change. The article does not mention what types of screening the participants underwent after the initial 5-year study period. This could potentially have an effect on the mortality numbers, if women decided to stop their screening after the study period ended. This study did not address differences in quality of life, such as discomfort from mammograms and additional procedures from false-positive screenings.
OUTCOMES MEASURED: Breast cancer mortality was the primary outcome. The tumor size and number of lymph node–positive cancers were also reported.
RESULTS: Only 54 of the original participants were excluded from the analysis. At the 13-year follow-up there were 107 breast cancer deaths in the combined mammography plus CBE group and 105 deaths in the CBE-only group (rate ratio=1.02; 95% confidence interval, 0.78-1.33). A total of 622 invasive and 71 in situ cancers were found in the combined group and 610 invasive and 16 in situ cancers were identified in the CBE-only group. Mammography was able to detect a cancer 2.1 years earlier than CBE alone. However, this lead time did not appear to improve survival. Overall, the tumors identified by mammography were smaller. There was no significant difference between the 2 groups in the number of lymph node–positive cancers detected by the end of the study. As expected, there were approximately 3 times as many biopsies and more diagnostic tests performed in the mammogram group.
This study found that in women 50 to 59 years the addition of annual screening mammograms to a very thorough clinical breast examination does not reduce breast cancer mortality over a 13-year follow-up. Although cancer detection rates were slightly higher in the mammogram group, there was also a 3-fold increase in the number of biopsies. This study might be reassuring in those parts of the world where mammography is not readily accessible. However, it is unlikely that these results will change practice in the current United States health care environment. In patients who refuse mammography, a thorough CBE may be as effective.