Feature | February 12, 2014

Annual Screening Does Not Cut Breast Cancer Deaths, Suggests Canadian Study

Value of breast screening should be reassessed

mammogram, mammography

Photo courtesy of Hologic

Annual screening in women aged 40-59 does not reduce mortality from breast cancer beyond that of physical examination or usual care, concludes a 25-year study from Canada published on bmj.com.

Furthermore, the study shows that 22 percent of screen detected breast cancers were over-diagnosed, representing one over-diagnosed breast cancer for every 424 women who received screening in the trial. Over-diagnosis refers to the detection of harmless cancers that will not cause symptoms or death during a patient's lifetime.

Regular mammography screening is done to reduce mortality from breast cancer. Women with small (non-palpable) breast cancer detected by screening have better long term survival than women with palpable breast cancer. But it is not clear whether this survival difference is a consequence of organised screening or of lead time bias (when testing increases perceived survival time without affecting the course of the disease) and over-diagnosis.

So researchers based in Toronto, Canada decided to compare breast cancer incidence and mortality up to 25 years in over 89,000 women aged 40-59 who did or did not undergo mammography screening.

Women in the mammography arm of the trial had a total of five mammography screens (one a year over a five year period), while those in the control arm were not screened.

Women aged 40-49 in the mammography arm – and all women aged 50-59 in both arms – also received annual physical breast examinations. Women aged 40-49 in the control arm received a single examination followed by usual care in the community.

During the 25 year study period, 3,250 women in the mammography arm and 3,133 in the control arm were diagnosed with breast cancer and 500 and 505, respectively, died of breast cancer. "Thus, the cumulative mortality from breast cancer was similar between women in the mammography arm and in the control arm," said the authors.

At the end of the five year screening period, an excess of 142 breast cancers occurred in the mammography arm compared with the control arm, and at 15 years the excess remained at 106 cancers. This, say the authors, implies that 22 percent of the screen detected invasive cancers in the mammography arm were over-diagnosed – that is, one over-diagnosed breast cancer for every 424 women who received mammography screening in the trial.

They stress that these results may not be generalisable to all countries, but say, in technically advanced countries, "our results support the views of some commentators that the rationale for screening by mammography should be urgently reassessed by policy makers."

While they believe that education, early diagnosis, and excellent clinical care should continue, they conclude that annual mammography "does not result in a reduction in breast cancer specific mortality for women aged 40-59 beyond that of physical examination alone or usual care in the community."

In an accompanying editorial, Mette Kalager, M.D., and colleagues believe that long term follow-up does not support screening women under 60.

They agree with the study authors that "the rationale for screening by mammography be urgently reassessed by policy makers," but point out that this is not an easy task "because governments, research funders, scientists, and medical practitioners may have vested interests in continuing activities that are well established."

For more information: www.bmj.com

Related Content

California Women In Favor of Extending State's Breast Density Inform Law
News | Breast Density | June 15, 2018
A recent survey of California women found that 95 percent of respondents want the state’s breast density inform law to...
Women More Likely to Use Other Preventive Health Services Following Mammography
News | Mammography | June 13, 2018
Medicare beneficiaries who undergo breast cancer screening with mammography are more likely than unscreened women to...
How AI and Deep Learning Will Enable Cancer Diagnosis Via Ultrasound

The red outline shows the manually segmented boundary of a carcinoma, while the deep learning-predicted boundaries are shown in blue, green and cyan. Copyright 2018 Kumar et al. under Creative Commons Attribution License.

News | Ultrasound Imaging | June 12, 2018 | Tony Kontzer
June 12, 2018 — Viksit Kumar didn’t know his mother had...
Breast imaging technologies have seen a rapid evolution.

Breast imaging technologies have seen a rapid evolution.

Feature | Women's Health | June 05, 2018 | By Jeff Zagoudis
Breast imaging technologies have evolved rapidly in the last two decades to help physicians detect breast cancers at
Breast Cancer Survivors Not Getting Recommended Number of Mammograms Post-Surgery
News | Mammography | May 24, 2018
Breast cancer survivors are not getting the recommended level of screening post-surgery, according to a newly-published...
Breast Cancer Places Greater Financial Burden on Black Women
News | Women's Health | May 16, 2018
Having breast cancer placed a significantly greater financial strain on black women than white women, according to a...
FDA's MQSA Accreditation Bodies Approved for Tomosynthesis Accreditation

Image courtesy of Fujifilm.

Feature | Mammography | May 14, 2018
On April 9, 2018, the U.S. Food and Drug Administration (FDA) announced that all four of its Mammography Quality...
Overlay Init