Despite Recent Arguments, Breast Cancer Screening Saves Lives

By Denise Reynolds

British researchers have taken on recent critics of regular screening for breast cancer and found that mammograms save the lives of two women for every one that is given unnecessary treatment and that the benefits clearly outweigh the harm.

Stephen Duffy of Queen Mark, University of London conducted two studies into the risks and benefits of breast cancer screening programs.  The first predicted the number of women who would have died from breast cancer in Britain if the screening programs there had not been launched back in 1988.  The second evaluated the number of breast cancer deaths among 80,000 Swedish women, comparing those offered screening with those who were not. 

The results, which are published in the Journal of Medical Screening, showed for every 28 cases diagnosed, between 2 and 2.5 lives were saved and one case was over-diagnosed, resulting in a “substantial and significant reduction in breast cancer deaths.”

Recently, the FDA has launched an investigation regarding over-screening of Americans using diagnostic imaging methods, such as CT scans, that emit radiation.  Mammograms are a specific type of imaging that uses a low-dose x-ray system to examine the breasts and the effective radiation dose from a mammogram is about 0.7 mSv, which is about the same as the average person receives from background radiation in three months, according to information published by the American College of Radiology (ACR) and the Radiological Society of North American (RSNA).

An alternative is called digital mammography that uses solid-state detectors that convert x-rays into electrical signals.  The electrical signals are used to produce images of the breast that can be seen on a computer screen or printed on film similar to conventional mammograms.

There is a risk of false positives with all mammogram procedures.  Five to 15 percent of screening mammograms require more testing, such as additional mammograms or ultrasound and most of these turn out to be normal.  The ACR/RSNA estimates that a woman who has a yearly mammogram between the ages of 40 and 49 has about a 30% chance of having a false-positive sometime in that decade.

"Unfortunately, we haven't yet got a flawless screening test, and some cases that are picked up wouldn't have needed treatment," said Duffy.  "But for every case like this, screening saves two women who would have otherwise died from breast cancer," he said.

Sara Hiom of Cancer Research UK says that she hoped the study would reassure women that screening was, in fact, valuable.  “What we need to remember of course is that detecting cancer earlier generally means improved survival.”

Breast cancer is the most common cancer in women worldwide, accounting for around 16 percent of all female cancers. It kills around 519,000 people globally each year.