New research suggests that more than one-third of women diagnosed with breast cancer are told that their condition is worse than it actually is, resulting in unnecessary treatments and placing women at risk for future health problems caused by those cancer treatments.
In a study published this month in the Annals of Internal Medicine, researchers from Denmark found that up to nearly half of women diagnosed with breast cancer have less invasive forms of cancers that don’t need to be treated.
Researchers evaluated data on women in Denmark between the ages of 35 and 84 years from 1980 to 2010. The study offered biennial mammography for women 50 to 69, beginning in different regions at different times.
The study focused on the incidence of advanced cancer, which includes tumors greater than 20 mm, and non-advanced cancer, which involves tumors less than 20 mm, in screened and non-screened women.
Using one approach, researchers compared the incidence of advance and nonadvanced tumors among women 50 to 84 years old in screening and nonscreening areas. They found 271 invasive breast cancer tumors and 179 ductal carcinoma in situ (DCIS) lesions were over diagnosed in 2010. That was the equivalent of an over-diagnosis rate of 24% and 15%, respectively.
When researchers used an approach which accounted for regional differences in women ages 35 to 84, they found that 711 invasive tumors and 180 cases of DCIS were over-diagnosed in 2010. This was the equivalent of an over-diagnosis rate of 48% and 38%.
The findings suggest that about one in every three women with breast cancer are over diagnosed, meaning they are told their condition is more serious than it really is.
The study is not the first to indicate women are being over-diagnosed with breast cancer. Research published in October indicated four times as many breast cancer tumors are misdiagnosed because of early mammograms.
Harvard researchers published a study in 2015 which found that more than $4 billion is spent annually on unnecessary breast cancer treatments that were misdiagnoses or over diagnoses; cases that did not pose a threat to the patient.
Researchers warn that over diagnosis is a problem that poses serious risks. Often the small tumors that are detected are slow growing, harmless and don’t need to be treated at all.
Not all breast cancer tumors are the same or pose the same risk. While some tumors are invasive, others stop growing and sometimes shrink.
An over-diagnosis can result in unnecessary chemotherapy and radiation treatment, exposure to extremely harsh medications, and unnecessary mastectomies and other surgeries, which always carry some level of risk.
Health advocates say while mammograms don’t find all breast cancer tumors, early screening reduces the risk of death from breast cancer by 25% to 31%.
More than 250,000 cases of breast cancer are diagnosed each year, causing more than 41,000 deaths, according to the American Cancer Society. About 63,000 women will be diagnosed with DCIS, which does not invade the tissue around it and is considered the earliest stage of breast cancer. However, most doctors treat DCIS the same way as invasive cancers. Researchers say that is a practice that may need to be reconsidered.