Breast Cancer Screening May Be Riskier for Women Over 70

Breast cancer screenings for older women led to small change in rate of late stage cancer

(RxWiki News) Mammograms can be a lifesaving tool, but older women undergoing this breast cancer screening may be at a higher risk for misdiagnosis.

A recent study looked at the effects of a breast cancer screening program that began testing women older than 70. The researchers found more early cases of cancer, but the fall in cases of advanced cancer was minimal.

The authors of the study concluded that testing women older than 70 led to a risk of overdiagnosis and overtreatment. They suggested that women over 70 decide for themselves whether to continue screenings for breast cancer.

"Talk to your family physician about what cancer screenings you need."

Gerrit-Jan Liefers, a surgical oncologist at Leiden University Medical Centre, led the study.

According to the authors, breast cancer is the largest contributor to cancer deaths among women. Current guidelines recommend that women receive regular mammograms to screen for breast cancer.

This study focused on women in the Netherlands who were 70 or older.

The Netherlands extended its breast cancer screening program to cover women up to 75 in 1998. Before, the program only covered women up to age 69.

Researchers tracked cases of breast cancer among these older women from 1995 to 1997, 1998 to 2002 and 2003 to 2011.

They found that diagnoses of new cases of breast cancer in its early stages rose after the screening expansion began — by about 116 cases per 100,000 women.

However, diagnoses of advanced breast cancer decreased by 7 cases per 100,000 women.

The researchers said more screening led to overdiagnosis. Some patients were diagnosed with breast cancer even though they did not have it.

The authors of the study wrote that overdiagnosis and overtreatment could be costly and result in harmful side effects, especially in older women.

They concluded that "the harms and benefits of screening should be weighed on a personalized basis."

"This is a reasonable study where they found the incidence of advanced cancers decreased and the incidence of early cancers increased after the use of screening mammography in the age group 70-75," said Cary Kaufman, MD, FACS, a breast surgeon and specialist at Bellingham Regional Breast Center in Washington state. "That is a valid finding and supports the value of screening mammograms, yet the authors conclusions seem to misinterpret their data."

Dr. Kaufman explained that screening mammograms find cancers sooner than routine physical exams. "Thus," he said, "mammograms will find a stage 3 cancer when it is stage 2, a stage 2 cancer when it is stage 1 and so on. This study found that larger (stages 2, 3 and 4) breast cancers decreased while smaller (stage 1 and stage 0) breast cancers increased. Their data supports screening mammography in that age group."

Dr. Kaufman noted, though, that the authors of this study excluded stage 2 cancers — which he called "a very important group of cancers" — from their final statistics. "They excluded the very important finding of a dramatic lowering of stage 2 cancers in their final calculations in this study," he said.

He explained that before screening, stage 2 cancers were 47 percent of cases. After screening, however, they were only 28 percent of cases. "That is a dramatic effect of down-staging by screening mammography," he said.

Stage 2 cancers are 2 centimeters to 5 centimeters in size, while stage 1 cancers are less than 2 centimeters. "Essentially, screening mammography found cancers when they were half the size they were previously," Dr. Kaufman told dailyRx News.

"The effect of screening created a 60 percent decrease in the number of stage 2 patients accompanied by a 70 percent increase in stage 1 patients. Changing from stage 2 to stage 1 increases the survival rate of these patients according to national survival statistics comparing stage 1 and stage 2," he said.

"It is unfortunate that the authors didn't provide interpretations using all the data. The assumption that the 60 percent decrease in stage 2 patients was not worth including in the calculations and discussion seems erroneous," he said.

This study was published Sept. 15 in The BMJ.

The Alpe d'HuZes Foundation funded the research. The authors declared no conflicts of interest.

Review Date: 
September 17, 2014