Screening mammography begins to reduce breast cancer mortality at an age earlier than when most women begin screening.
A recently published study from the United Kingdom (UK) confirms that mammography screening, beginning at age 40, significantly reduces breast cancer mortality. The results appeared in Lancet Oncology in August 2020. These study results reaffirm the recommendations of the American College of Radiology and the Society of Breast Imaging. Both organizations recommend that most women begin annual mammography at age 40 – earlier than when most women have their first screening.
What does this UK study mean to us here in the United States?
The UK study provides valuable additional data for those of us in the breast imaging field. This recent update confirms, again, that annual breast cancer screening beginning at age 40 saves lives. Breast cancer death rates were reduced by approximately 25 percent for women who began screening at age 40, averting one death per 1,000 women screened, and this absolute gain remained constant until the end of the study. The UK study also confirmed that there is little fear of over-diagnosis in the 40-to-49 age category with a rate similar to what is commonly encountered in women over 50.
Selection Details of the UK Study
The UK Breast Screening Age Trial recruited 53,883 women to begin annual mammography screenings at age 40. Researchers placed twice as many women (106,953) in the control group. The control group participated in the UK’s National Health Service (NHS) standard breast cancer screening. The NHS provides breast cancer screenings to women aged 50 until age 71 every three years.
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Researchers sent randomly selected women invitations through the mail, offering annual breast cancer screening beginning at age 40. These women were recruited from general practitioners’ lists, held by Family Health Services Authorities. The women who responded were ages 39-to-41, from 23 breast screening sections in England, Scotland, and Wales.
Researchers also randomly chose women for the control group. These women were not aware of the research project and received the standard breast cancer screening with no departure from standard care.
The younger annual mammogram group received annual mammograms until they received their invitation from NHS for breast screening. The control group of women began their breast cancer screenings once they reached age 50, following NHS recommendations.
Recruitment began on October 14, 1990, and ended on September 24, 1997. Researchers followed patients for a median time of 22.8 years.
Procedures Used in the Trial
The trial used two-view film (analog) mammography for each participant’s first screening. Afterward, single view was utilized. The local facility staff double-read each participant’s mammogram. If a woman moved, she could self-refer to the nearest center taking part in the trial. Women in the trial transitioned to the regular NHS breast cancer screening program once they received their invitation around age 50.
The NHS Central Register and all trialists were notified of every breast cancer diagnosis, breast cancer death, and other death causes for trial members through February 28, 2017.
The primary endpoint for the UK Breast Screening Age Trial was death by breast cancer in both groups. Researchers compared deaths from both groups that occurred before their invitation to the standard NHS breast screening program.
Participation from screening invitations was similar in both groups of women:
Researchers saw a significant difference in death rates from breast cancer by 10 years. The interventional group experienced just 83 deaths compared to 219 deaths in the control group. There was no significant difference during the next 10-plus years of follow-up. Of the breast cancer deaths, 126 occurred in the early intervention study group and 255 in the control group.
The newest study update comes 23 years after recruitment ended. The study confirms that annual breast cancer screenings that begin at age 40 reduce breast cancer mortality.
In summary, the UK study confirms that screening mammography beginning at age 40 significantly reduces breast cancer mortality as compared to women who wait to begin screening mammography until age 50. These findings validate both the ACR and the SBI recommendations that women of average risk begin having annual mammograms beginning at age 40.
“Breast cancer screening saves lives, annual screening mammography beginning at age 40 saves the most lives.”
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Daniel Shekleton, M.D., is a breast imaging radiologist and breast intervention specialist with Raleigh Radiology. He is a member of the RSNA, ACR, and SBI. He earned his bachelor’s degree at the U.S. Military Academy at West Point and completed his medical degree and residency in radiology and internal medicine at the Southern Illinois University School of Medicine. He joined Raleigh Radiology in 2019.