MONDAY, Feb. 23, 2004 (HealthDayNews) -- New research shows breast cancer screening can save lives; in some cases, up to 20 years later.
Two studies, appearing in the Feb. 23 online edition of Cancer, found that when breast cancer tumors are detected early, women have a better chance of survival.
One study followed women with breast cancer for 20 years to evaluate if the stage of the cancer at the time of diagnosis made any difference up to two decades later. The other study tracked the introduction of a mass screening program and found women with breast cancer detected at screening tended to have a better prognosis than women whose cancers were detected between screenings.
Nearly 216,000 women will be diagnosed with breast cancer in the United States this year, and more than 40,000 will die from the disease, according to the American Cancer Society. The society recommends that every woman over 40 have an annual mammogram to check for breast cancer.
"Our study's results show that the size and node status of a tumor continue to influence survival for many years after diagnosis," says Jane Warwick, a research fellow at Cancer Research UK in London and author of the first study. "This suggests that early detection is still conferring a benefit many years later."
Warwick and her colleagues examined more than 20 years of data from Swedish women, aged 40 to 74, diagnosed with breast cancer. The researchers looked at the effect that tumor size, tumor grade and lymph node involvement had on long-term survival. As time progressed, the researchers found the effects from these factors diminished, but did not disappear.
"The influence of these tumor attributes on survival was smaller in later years, but still present, contrary to the widespread belief that the tumor attributes at diagnosis no longer affect survival after 10 years or so," Warwick says.
"The classic predictors of prognosis are still good predictors 20 years down the line," says Dr. Jay Brooks, chief of hematology and oncology at the Ochsner Clinic Foundation Hospital in New Orleans.
Brooks says this information is important because it gives clinicians confirmation that they can continue to use tumor attributes when making treatment decisions five or 10 years after cancer diagnosis.
The other study followed the 1992 introduction of biannual breast cancer screening for women between the ages of 50 and 69 in one town in the Netherlands until 1999. The researchers also looked at women diagnosed with breast cancer between 1985 and 1992.
"With the introduction of the breast cancer screening program, much attention was paid to the expected increase in breast-conserving surgery and decrease in mortality rates," says study author Dr. Miranda Ernst, who was a surgical resident at St. Elisabeth Hospital in Tilburg, The Netherlands, at the time of the study.
During the 14-year study period, 1,400 women were diagnosed with breast cancer. Surprisingly, only 40 percent of the women had their cancer detected at screening, while nearly 30 percent were diagnosed between screenings.
The researchers didn't find any statistically significant change in the rate of breast-conserving surgery.
However, breast cancer screening still had a positive influence. According to Ernst, after the introduction of screening, women aged 50 to 69 had a better prognosis and smaller tumors than before screening was implemented.
Brooks says he was surprised by the large number of women who developed breast cancer between screenings in this study, and says it points to the need to be screened at a place that does a lot of breast cancer screenings.
"Mammograms should be done by people who do lots of them, because they're better at it," notes Brooks, who recommends getting your mammogram done at a center that does at least 200 mammograms a month.