Stunning Allegation: Half of all mastectomy patients do NOT have cancer gene; Misreading data?

Since actress Angelina Jolie had a preventative double mastectomy based on foreboding genetic testing in 2013, a study of 2,000 cancer patients conducted by Stanford University found that roughly half of those who opted for a bilateral mastectomy had a gene variant that may have been harmless.

All of the patients in the study had been recently diagnosed with cancer and had been tested for the BRCA1 and BRCA2 genetic mutations prior to having a bilateral, or double, mastectomy.

The study found that half of the women who had a bilateral mastectomy after having the genetic testing had variants of uncertain significance, or VUS, which may not correspond to a higher cancer risk.

The genetic testing has become more common because it is less expensive than it used to be. But interpretations of the results can be complicated and confusing.

Between 25 and 50 percent of the breast cancer surgeons admitted to treating women with the VUS  the same way they would treat women with known cancer-associated variants.  This may have led less-experienced surgeons to recommend aggressive bilateral mastectomy when the involvement of a genetic counselor might have led to a different result.

In a review of the study on the Stanford Medicine News Center, Allison Kurian, MD, said, “Our findings suggest a limited understanding among physicians and patients of the meaning of genetic testing results.”

An earlier study, conducted in February, found that doctors often did not recommend genetic testing for breast cancer patients who were at high risk for carrying the BRCA1 or BRCA2 genes.

That study surveyed 2,502 women who had recently been diagnosed with breast cancer. Among them, 666 had received the genetic testing — with 59% of that group testing positive for the genes. A quarter of that group did not have the testing done until after completing surgery. Women without private medical insurance were more likely to have delayed testing.

“Our findings suggest that we are not maximizing the benefit of genetic testing for our patients with breast cancer because of barriers related to timeliness of testing and lack of expertise necessary to incorporate results into treatment decisions,” said University of Michigan researcher Steven Katz, MD, MPH.