EON

Toronto – Some types of breast cancer may actually go away on their own, according to a new study.

Led by Dr. Per-Henrik Zahl of the Norwegian Institute of Public Health, researchers looked at invasive breast cancer rates among 120,000 Norwegian women aged 50 to 64 who had a mammogram.

The women were compared to another group who did not have the regular breast cancer screenings, but were detected to have the disease.

They found no difference in breast cancer rates, and found hat 22% more invasive breast tumors were discovered in the group who had mammograms every two years.

“The problem is, we don’t know the natural history [of breast cancer],” said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La. “I am sure there are some that do regress. The problem is, we can’t pick up those that are going to regress. It’s one of the unanswerable questions.”

This shows that it is possible that some types of cancer may actually disappear on their own.

“Our findings simply provide new insight on what is arguably the major harm associated with mammographic screening, namely, the detection and treatment of cancers that would otherwise regress,” said the researchers led by Per-Henrik Zahl at the Norwegian Institute of Public Health‘s epidemiology department in Oslo.

The study was published in the Nov. 24 issue of the Archives of Internal Medicine.