Breast Cancer Screening in Vermont and Norway Has Similar Results

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A study compared the breast cancer screening approach used in Norway to the screening approach used in Vermont. The screening programs in the country and the state are different, but both seem to be equally good at identifying breast cancer.

Norway has firm national standards for healthcare. Norwegian women usually start getting mammograms at age 50. Mammograms are usually done every 2 years in Norway. Norwegian women are scheduled automatically for a mammogram at a specific time and place.

In Vermont (and most other places in the United States), breast cancer screening usually starts at age 40, 10 years earlier than in Norway. U.S. doctors usually recommend mammograms every year, but scheduling the mammogram is usually done by each woman.

Researchers looked at the health histories of more than 45,000 Vermont women and nearly 200,000 Norwegian women aged 50 to 69. Screening mammograms were done from 1997 to 2003.

The findings:

  • More than 95% of the Norwegian women had a mammogram every 2 years as planned. Only 3% of the women had more than 2 years between mammograms. Automatic scheduling might explain why just about all of the Norwegian women had mammograms as recommended.
  • More than 80% of the Vermont women had a mammogram every year as recommended. The need for U.S. women to schedule their own mammograms might explain why 17% of the Vermont women didn't get mammograms as recommended.
  • Breast cancer was about 40% more common in Vermont women compared to Norwegian women.
  • Compared to breast cancers found in Norwegian women, breast cancers found in Vermont women were more likely to be very small and not involve the lymph nodes:
    • about 56% of breast cancers found in Vermont women were 15 mm or smaller, compared to 38% of cancers found in Norwegian women
    • about 68% of breast cancers found in Vermont women didn't involve lymph nodes, compared to 57% of cancers found in Norwegian women
  • Norwegian women were less likely than Vermont women to be called back for more evaluation because of a suspicious finding on a mammogram that eventually turned out not to be cancer.

Doctors compare the benefits of breast cancer screening to screening's costs and risks to make recommendations about how, when, and in whom screening should be done. The costs and risks of screening include the risk of more procedures and tests (and the worry that comes with them) if screening suggests a problem when nothing is wrong. Research has shown that the benefits of breast cancer screening outweigh the costs and risks for all women older than 50. In the United States, screening mammograms starting at age 40 are recommended, but some doctors feel that it's less clear if women between 40 and 50 get more benefits than risks from annual breast cancer screening.

In this study, most of the Vermont women had annual mammograms starting at age 40. Still, the Vermont approach to screening didn't seem any better overall than the Norwegian approach, where screening starts at 50 and is done every 2 years.

It's important to know that this research DOESN'T say that breast screening every other year (instead of every year) starting at age 50 (instead of age 40) makes sense for all women. This study compared two breast cancer screening approaches in two very different populations of women. The women differed in geography, ethnicity, and culture. Also, breast cancer characteristics and other aspects of healthcare delivery are fundamentally different between the two groups of women. Breast cancers found in Vermont women were more likely to be smaller and not involve the lymph nodes compared to Norwegian women, which could mean the long-term health outcomes of the U.S. women might be better than that of the Norwegian women if the two groups were followed for a longer time.

Still, research like this can help doctors develop better approaches to breast cancer screening. A system that automatically schedules mammograms for women, as in Norway, may increase the chances that women will get mammograms as recommended. In many parts of the United States women have a hard time scheduling mammograms and the number of women older than 40 who aren't getting regular mammograms has been increasing.

Until more is known, the recommendation is:

  • if you're 40 or older, you should have a screening mammogram every year

It's one of the best ways to ensure that any breast cancer is diagnosed early, when it's most easily treated. If your breast cancer risk is higher than average, talk to your doctor about a breast cancer screening plan tailored to your unique situation.

Visit the Breastcancer.org Screening and Testing section to learn more about breast cancer screening and mammograms.

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