The coverage of celebrities with breast cancer in the media may be influencing the steep rise in double mastectomy, a breast cancer expert says.

Over the past several years, there’s been increased media coverage of high-profile celebrities such as Angelina Jolie and Christina Applegate disclosing their breast cancer diagnosis and treatment, says Dr. Michael Sabel, chief of surgical oncology at the University of Michigan Comprehensive Cancer Center.

“People underestimate the impact of celebrity news reports on medical knowledge. It’s naïve to think this is not a source from where we get our medical information,” adds Sabel.

His research team analyzed 727 articles from major U.S. print publications that covered the story of 17 celebrity breast cancer diagnoses. Four celebrities underwent double mastectomy, and 45 percent of the media coverage about their diagnoses mentioned that. Of the 10 celebrities who had a single mastectomy or breast conserving therapy, 26 percent of the media coverage discussed it.

During that time, the number of women with breast cancer who underwent double mastectomy at the University of Michigan rose nearly five-fold, the study finds.

When Applegate was diagnosed with breast cancer in 2008, a family history and BRCA mutation influenced her decision to have a double mastectomy. The BRCA mutation meant she had a high risk of cancer returning in one breast or a new cancer developing in the other breast. It’s a detail that only a small proportion of media coverage included.  Then, in 2013, Angelina Jolie revealed that she had both breasts removed because a BRCA mutation put her at high risk of breast cancer, Sabel notes.

“In Angelina Jolie’s case, almost every single article explains why she had a bilateral mastectomy. Contrast that to Christina Applegate, who also had a BRCA mutation. That was rarely discussed in media articles,” says Sabel.

While many refer to the “Angeline Jolie effect” as influencing the rise in double mastectomy, it began earlier than that. Given the timing and the differences in media coverage, it might be more aptly deemed the “Christina Applegate effect,” he adds.

It’s not uncommon for celebrities to influence health trends, but the concern is that this one-sided coverage is leading to women choosing double mastectomy based on inaccurate information about the risks and benefits, says Sabel of the study, which appears in Annals of Surgical Oncology.