Breast Cancer Mortality Reduced by 26% With Mammography

New data from a large Swedish cohort suggest that screening mammography in women aged 40-49 years reduced the risk of breast cancer mortality by 26%, compared with women in that age group who were not screened. The results were presented Sept. 29 during a press briefing in advance of the annual Breast Cancer Symposium sponsored by the American Society of Clinical Oncology.

It’s widely accepted that screening mammography significantly reduces mortality in women aged 50-69 years, but the effectiveness of screening in women aged 40-49 years has been less clear.

Late last year, the U.S. Preventive Services Task Force issued new recommendations that women delay routine screening mammograms until age 50 years. The panel said that the risk of screening mammograms in this age group – including false-positive results, anxiety, and unnecessary and invasive treatments – outweighed the potential benefit in mortality reduction.

The recommendations generated controversy, prompting several medical organizations – the American Cancer Society, the American College of Radiology, and the American College of Obstetricians and Gynecologists, among others – to issue critical responses to the recommendations. These organizations argue that the benefits from screening mammography in this age group should not be underestimated and recommend that women aged 40-49 years continue to receive screening mammograms.

The new findings come from the SCRY cohort (Mammography Screening in Young Women), which may be the largest study of screening mammography in this age group. Currently, there are about Swedish 600,000 women aged 40-49 years. However, over the study period – 1986 to 2005 – more than 1 million women fell within this age group. In 1986, Sweden adopted national breast cancer screening guidelines, under which screening mammography was considered optional for women aged 40-49 years and 70-74 years.

By chance, roughly half of the counties in Sweden opted to invite women in the 40- to 49-year-old age group for screening mammograms, setting up the possibility of a head-to-head comparison of screening and no screening in this age group, according to Håkan Jonsson, Ph.D., of the department of cancer epidemiology at Umeå (Sweden) University.

Women aged 40-49 years living in counties that extended the invitation were included in the study group; eligible women living in the remaining counties that did not invite the women to participate comprised the control group. The average follow-up was 16 years. Women in the study group were followed from the time of their first screening; controls were followed from a corresponding time point.

The researchers refined mortality to include only those women who were diagnosed with breast cancer after the start of screening and who were aged 40-49 at the time of diagnosis.

Women in the study group had a 26% lower risk of dying from breast cancer than did those in the control group, when the researchers included all women who were invited for screening. In this analysis, 619 women in the study group died of breast cancer, compared with 1,205 in the control group.

When only those who actually participated in screening were included, women in the study group had a 29% lower risk of dying from breast cancer. In this analysis, 523 women in the study group died of breast cancer, compared with 1,205 in the control group. The researchers also found that 1,250 women would need to be screened in order to save one life.

They also looked at breast cancer deaths in an earlier “reference” period (1970-1985) when screening was not in effect, in order to ensure that the difference in mortality was because of screening alone. There was a nonsignificant 6% reduction in breast cancer mortality in the study group.

These findings bolster arguments for routine breast cancer screening for women aged 40-49 years, which have recently been challenged. A Norwegian study published in the New England Journal of Medicine in the Sept. 23, 2010, issue reinvigorated the controversy. In the study, the availability of screening mammography accounted for a 10% relative reduction in deaths from breast cancer from 1996 through 2005.

The study included more than 40,000 women with breast cancer; screening mammography was offered to women aged 50-69 years. The 10% number is less than the previous estimates in the United States of 15%-23% reductions in breast cancer mortality to because of mammograms. In addition, Norwegian researchers attributed some of the drop in breast cancer deaths to other factors, such as better treatment and awareness of the disease.

The controversy has left women in this age group – and their physicians – confused about what they should be doing with regard to breast health, according to Dr. Jennifer C. Obel, who moderated the press conference. Dr. Obel is a medical oncologist at NorthShore University HealthSystem and the University of Chicago.

“Many women aged 40-49 [years] want unambiguous recommendations regarding whether to undergo mammography. While the optimal scheduling of regular mammograms continues to be discussed by experts in the field, I think the critical message is that all women, beginning at age 40, should speak with their doctors about mammography to try to understand the potential benefits and risks of the test and to determine what is best for them as individuals,” she said.

Disclosures: The authors noted that they had no relevant financial disclosures.

New data from a large Swedish cohort suggest that screening mammography in women aged 40-49 years reduced the risk of breast cancer mortality by 26%, compared with women in that age group who were not screened. The results were presented Sept. 29 during a press briefing in advance of the annual Breast Cancer Symposium sponsored by the American Society of Clinical Oncology.

It’s widely accepted that screening mammography significantly reduces mortality in women aged 50-69 years, but the effectiveness of screening in women aged 40-49 years has been less clear.

Late last year, the U.S. Preventive Services Task Force issued new recommendations that women delay routine screening mammograms until age 50 years. The panel said that the risk of screening mammograms in this age group – including false-positive results, anxiety, and unnecessary and invasive treatments – outweighed the potential benefit in mortality reduction.

The recommendations generated controversy, prompting several medical organizations – the American Cancer Society, the American College of Radiology, and the American College of Obstetricians and Gynecologists, among others – to issue critical responses to the recommendations. These organizations argue that the benefits from screening mammography in this age group should not be underestimated and recommend that women aged 40-49 years continue to receive screening mammograms.

The new findings come from the SCRY cohort (Mammography Screening in Young Women), which may be the largest study of screening mammography in this age group. Currently, there are about Swedish 600,000 women aged 40-49 years. However, over the study period – 1986 to 2005 – more than 1 million women fell within this age group. In 1986, Sweden adopted national breast cancer screening guidelines, under which screening mammography was considered optional for women aged 40-49 years and 70-74 years.

By chance, roughly half of the counties in Sweden opted to invite women in the 40- to 49-year-old age group for screening mammograms, setting up the possibility of a head-to-head comparison of screening and no screening in this age group, according to Håkan Jonsson, Ph.D., of the department of cancer epidemiology at Umeå (Sweden) University.

Women aged 40-49 years living in counties that extended the invitation were included in the study group; eligible women living in the remaining counties that did not invite the women to participate comprised the control group. The average follow-up was 16 years. Women in the study group were followed from the time of their first screening; controls were followed from a corresponding time point.

The researchers refined mortality to include only those women who were diagnosed with breast cancer after the start of screening and who were aged 40-49 at the time of diagnosis.

Women in the study group had a 26% lower risk of dying from breast cancer than did those in the control group, when the researchers included all women who were invited for screening. In this analysis, 619 women in the study group died of breast cancer, compared with 1,205 in the control group.

When only those who actually participated in screening were included, women in the study group had a 29% lower risk of dying from breast cancer. In this analysis, 523 women in the study group died of breast cancer, compared with 1,205 in the control group. The researchers also found that 1,250 women would need to be screened in order to save one life.

They also looked at breast cancer deaths in an earlier “reference” period (1970-1985) when screening was not in effect, in order to ensure that the difference in mortality was because of screening alone. There was a nonsignificant 6% reduction in breast cancer mortality in the study group.

These findings bolster arguments for routine breast cancer screening for women aged 40-49 years, which have recently been challenged. A Norwegian study published in the New England Journal of Medicine in the Sept. 23, 2010, issue reinvigorated the controversy. In the study, the availability of screening mammography accounted for a 10% relative reduction in deaths from breast cancer from 1996 through 2005.

The study included more than 40,000 women with breast cancer; screening mammography was offered to women aged 50-69 years. The 10% number is less than the previous estimates in the United States of 15%-23% reductions in breast cancer mortality to because of mammograms. In addition, Norwegian researchers attributed some of the drop in breast cancer deaths to other factors, such as better treatment and awareness of the disease.

The controversy has left women in this age group – and their physicians – confused about what they should be doing with regard to breast health, according to Dr. Jennifer C. Obel, who moderated the press conference. Dr. Obel is a medical oncologist at NorthShore University HealthSystem and the University of Chicago.

“Many women aged 40-49 [years] want unambiguous recommendations regarding whether to undergo mammography. While the optimal scheduling of regular mammograms continues to be discussed by experts in the field, I think the critical message is that all women, beginning at age 40, should speak with their doctors about mammography to try to understand the potential benefits and risks of the test and to determine what is best for them as individuals,” she said.

Disclosures: The authors noted that they had no relevant financial disclosures.

New data from a large Swedish cohort suggest that screening mammography in women aged 40-49 years reduced the risk of breast cancer mortality by 26%, compared with women in that age group who were not screened. The results were presented Sept. 29 during a press briefing in advance of the annual Breast Cancer Symposium sponsored by the American Society of Clinical Oncology.

It’s widely accepted that screening mammography significantly reduces mortality in women aged 50-69 years, but the effectiveness of screening in women aged 40-49 years has been less clear.

Late last year, the U.S. Preventive Services Task Force issued new recommendations that women delay routine screening mammograms until age 50 years. The panel said that the risk of screening mammograms in this age group – including false-positive results, anxiety, and unnecessary and invasive treatments – outweighed the potential benefit in mortality reduction.

The recommendations generated controversy, prompting several medical organizations – the American Cancer Society, the American College of Radiology, and the American College of Obstetricians and Gynecologists, among others – to issue critical responses to the recommendations. These organizations argue that the benefits from screening mammography in this age group should not be underestimated and recommend that women aged 40-49 years continue to receive screening mammograms.

The new findings come from the SCRY cohort (Mammography Screening in Young Women), which may be the largest study of screening mammography in this age group. Currently, there are about Swedish 600,000 women aged 40-49 years. However, over the study period – 1986 to 2005 – more than 1 million women fell within this age group. In 1986, Sweden adopted national breast cancer screening guidelines, under which screening mammography was considered optional for women aged 40-49 years and 70-74 years.

By chance, roughly half of the counties in Sweden opted to invite women in the 40- to 49-year-old age group for screening mammograms, setting up the possibility of a head-to-head comparison of screening and no screening in this age group, according to Håkan Jonsson, Ph.D., of the department of cancer epidemiology at Umeå (Sweden) University.

Women aged 40-49 years living in counties that extended the invitation were included in the study group; eligible women living in the remaining counties that did not invite the women to participate comprised the control group. The average follow-up was 16 years. Women in the study group were followed from the time of their first screening; controls were followed from a corresponding time point.

The researchers refined mortality to include only those women who were diagnosed with breast cancer after the start of screening and who were aged 40-49 at the time of diagnosis.

Women in the study group had a 26% lower risk of dying from breast cancer than did those in the control group, when the researchers included all women who were invited for screening. In this analysis, 619 women in the study group died of breast cancer, compared with 1,205 in the control group.

When only those who actually participated in screening were included, women in the study group had a 29% lower risk of dying from breast cancer. In this analysis, 523 women in the study group died of breast cancer, compared with 1,205 in the control group. The researchers also found that 1,250 women would need to be screened in order to save one life.

They also looked at breast cancer deaths in an earlier “reference” period (1970-1985) when screening was not in effect, in order to ensure that the difference in mortality was because of screening alone. There was a nonsignificant 6% reduction in breast cancer mortality in the study group.

These findings bolster arguments for routine breast cancer screening for women aged 40-49 years, which have recently been challenged. A Norwegian study published in the New England Journal of Medicine in the Sept. 23, 2010, issue reinvigorated the controversy. In the study, the availability of screening mammography accounted for a 10% relative reduction in deaths from breast cancer from 1996 through 2005.

The study included more than 40,000 women with breast cancer; screening mammography was offered to women aged 50-69 years. The 10% number is less than the previous estimates in the United States of 15%-23% reductions in breast cancer mortality to because of mammograms. In addition, Norwegian researchers attributed some of the drop in breast cancer deaths to other factors, such as better treatment and awareness of the disease.

The controversy has left women in this age group – and their physicians – confused about what they should be doing with regard to breast health, according to Dr. Jennifer C. Obel, who moderated the press conference. Dr. Obel is a medical oncologist at NorthShore University HealthSystem and the University of Chicago.

“Many women aged 40-49 [years] want unambiguous recommendations regarding whether to undergo mammography. While the optimal scheduling of regular mammograms continues to be discussed by experts in the field, I think the critical message is that all women, beginning at age 40, should speak with their doctors about mammography to try to understand the potential benefits and risks of the test and to determine what is best for them as individuals,” she said.

Disclosures: The authors noted that they had no relevant financial disclosures.