• Anita Hollerer-Squire

How safe are mammograms?

Updated: Jun 14


Lately I have put off getting a mammogram, mainly because I worry about the negative effect that could result from the radiation. But how bad is the radiation from a mammogram really and is it worth the risk? What alternatives are there?

I started getting mammograms in my early 40's - every second year. If you've ever had one, you will know that they are not exactly pleasant. But if they can detect breast cancer, I figured it's worth it. Then, a few years ago, I started hearing about the negative effects mammograms can have and consequently haven't had another one since. The more I learnt, the more I asked myself why I would look for breast cancer with a test that can actually be the cause of breast cancer?

Mammograms - to have or not to have

On one hand you have doctors and the breast cancer foundations encouraging regular mammograms, on the other hand you have experts warning about the long term exposure risks to radiation and the high percentage of false positiives that lead to treatment without being necessary. Who should we believe? I did some research and here are the pros and cons I could find:

A Swedish study published in the journal Radiology in 2011 was the longest ever trial of mammograms for breast cancer detection. It was also the first to track the effects of this screening method alone on breast cancer mortality. After following more than 133,000 women, ages 40 to 74, over a period of nearly 30 years, the researchers found that women who had a mammogram were 30 percent less likely to die from breast cancer compared to women who didn't have mammograms. For every 414 women screened with a mammogram over a seven-year period, one breast cancer death was prevented.

A 2010 Norwegian study, which was led by researchers at the Harvard School of Public Health, also found a lifesaving benefit from mammograms—although it wasn't as significant. The researchers looked at data from about 40,000 women who took part in the Norwegian breast cancer screening program. The study found that mammogram screening only reduced the rate of breast cancer death by about 10 percent in women ages 50 to 69. The reduction was less—8 percent—in women over age 70. Yet a follow-up to the study noted that six to 10 out of every 2,500 women screened were "overdiagnosed," meaning tumors were found and treated that were never likely to become life threatening.

A newer breast cancer screening technology - tomosynthesis - supposedly creates more detailed 3D images of the breast tissue than the standard 2D mammogram. Some researchers say it can help detect the disease earlier than a conventional mammogram. Other health experts say that they don't have better success rates than the standard mammogram. The radiation dose is similar to that of a normal mammogram.

On average the total radiation dose for a standard 2D mammogram with 2 views of each breast is anywhere between 0.44 - 1 millisieverts, or mSv. (mSv is a measure of radiation dose). The amount of radiation needed also depends on breast density and on breast size. Furthermore, dose levels are known to vary between clinics and systems used. An example is a study done by Wallis, where patients were examined both in England and in Sweden, with an average breast dose per DBT scan (digital breast tomosynthesis) that was about 17% higher in