The study reviewed here 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:
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:
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.
BURLINGTON, Vt., July 29 (MedPage Today) -- Breast cancer screening programs in Vermont and Norway got similar results, despite significant differences in approach, researchers here said.
Screening mammography detected cancer at about the same rate and the same stage in the two areas, according to Berta Geller, Ed.D., of the University of Vermont, and colleagues.
But, women in Norway -- enrolled in an organized population-based screening program -- were recalled for additional imaging significantly less often (P<0.001) than women in Vermont, the researchers reported in the July 29 online issue of the Journal of the National Cancer Institute.
On the other hand, women in Vermont -- whose "opportunistic" screening was based on physician referral -- had significantly more cancers detected (P<0.001) during the intervals between mammograms, the researchers said.
Comparing systems of screening delivery is challenging, Dr. Geller and colleagues noted, because of differences in such factors as screening interval, the age of the target population, and the algorithms that are used to manage mammographic abnormalities.
In this case, however, the bottom line is that "either one of [these two] is fine" in terms of results, Dr. Geller said.
In Norway, all women in a specified age range regularly receive a personal letter that invites them to have a mammogram at an assigned time and place. In Vermont, screening is usually initiated by a suggestion from a primary care provider and the patient chooses where to have the test.
In Vermont, most women have a mammography every one or two years, beginning at age 40; in Norway, women ages 50 through 69 have a scheduled mammogram every two years.
To compare the systems, Dr. Geller and colleagues looked at recall rates, rates of screen-detected and interval cancers, and prognostic tumor characteristics of women ages 50 through 69 who had mammograms in the two regions from 1997 through 2003.
In Vermont, 45,050 women had on average 3.1 mammograms during the study period, with a one-year interval for 83% and an interval of more than two years for only 7%.
In Norway, 194,430 women had on average 1.9 mammograms during the study period, 97% of them at two-year intervals and only 3% at an interval of greater than two years.
Analysis found:
Prognostic characteristics of all invasive cancers -- detected both at screening and during the interval -- were similar in Vermont and Norway, the researchers said.
The researchers said it's possible that some results were influenced by "subtle differences in the Vermont and Norwegian data definitions and collection procedures."
They added that not all variables that influence screening accuracy were collected in both countries and the absence of one-year screening intervals in Norway made it hard to distinguish the effects of screening interval from other possible differences in mammography performance.
The study was supported by the NCI and the Cancer Registry of Norway. The researchers did not report any conflicts.
Primary source: Journal of the National Cancer Institute Source reference: Hofvind S, at al "Comparing screening mammography for early breast cancer detection in Vermont and Norway" J Natl Cancer Inst 2008; 100: 1082-1091.
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