Regular breast cancer mammogram may be resulting in "widespread overdiagnosis," leading to some women receiving unnecessary treatment for tumors that might not have led to illness or death, a study suggests.

In regions of the United States where high levels of mammograms were conducted, there was an increased diagnosis of tumors -- but death cancer rates were no lower than in areas where screenings were fewer, the researchers say.

"The simplest explanation is widespread overdiagnosis, which increases the incidence of small cancers without changing mortality," the study authors write in JAMA Internal Medicine.

The concern, the researchers say, is that increases screening unintentionally results in overdiagnosis by detecting small, indolent or regressive tumors that would not otherwise require treatment.

Across U.S. counties, there was a correlation between the extent of mammogram screening and breast cancer incidence -- particularly small cancers -- but not with breast cancer mortality, they say.

When breast cancer screening increased by 10 percent, it led to doctors diagnosing breast cancer 16 percent more often overall, with a 25 percent increase in the diagnosis of small tumors, 2 centimeters or smaller, the researcher found.

However, increased screening did not have a significant impact on the number of women dying from breast cancer in the 10 years following a mammogram, they determined.

Some cancer experts were quick to weigh in with cautions that the study should not push women to believe mammograms are unnecessary or can be skipped.

"My biggest concern with this article is the hint or suggestion that mammography screening does not reduce mortality," said Dr. Richard Wender, chief cancer control officer for the American Cancer Society. "That question has been decided. There's no longer any debate about whether mammography saves lives."

Other research has shown mammography can yield a 20 percent reduction in death rates from breast cancer for women aged 40 and above, said Wender, who was not a part of the published study.

The U.S. Preventive Services Task Force recommends average-risk women should have mammograms every other year between ages 50 and 74.

Dr. Harold Burstein at the Dana-Farber Cancer Institute in Boston agreed but said the study should be taken as a chance to re-visit the issue of mammogram screenings.

"Mammograms are still important, but we still need to figure out which women really need mammograms and on which schedule," said Burstein, who was also not involved in the study.

Women and their doctors might want to consider discussing what mammograms can or can't provide before simply opting for a mammogram annually, he suggested.

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