Genetic screening could reduce number of breast cancer cases

Genetic screening for breast cancer could help women make choices to limit the disease, researchers say.

Alice Whittemore

Should every newborn baby girl be genetically screened for breast-cancer risk? That isn’t cost-effective — yet. But if it were, would it be worthwhile?

A previous study said no. But in a paper published Oct. 23 in Cancer Epidemiology, Biomarkers & Prevention, researchers at the School of Medicine suggest otherwise.

Alice Whittemore, PhD, professor of health research and policy, and her team examined 86 gene variants known to increase the chances of breast cancer. They created a computer model that accounted for the prevalence of each variant and the associated risk of breast cancer. Each possible combination of gene variants created with the model was then ranked by the likelihood that it would cause breast cancer within a woman’s lifetime.

“It was quite a computational feat,” said Whittemore, who is senior author of the paper. The lead author is Weiva Sieh, MD, PhD, assistant professor of health research and policy.

The main takeaway message is we can be more optimistic than previously predicted about the value of genomic sequencing.

The team found that the riskiest top 25 percent of gene combinations predicted 50 percent of all future breast cancers. Those women would then have the opportunity to get regular mammograms, watch their diets and make childbearing and breast-feeding decisions with the awareness of their higher risk. Some women might even select, as actress Angelina Jolie did quite publicly, to have their breasts removed as a prophylactic measure.

“The main takeaway message is we can be more optimistic than previously predicted about the value of genomic sequencing,” Whittemore said. “But we still have a way to go in preventing the disease.”

“Our ability to predict the probability of disease based on genetics is the starting point,” Sieh said. “If a girl knew, from birth, what her inborn risk was, she could then make more informed choices to alter her future risk by altering her lifestyle factors. We also need better screening methods and preventative interventions with fewer side effects.”

“We want to focus on those at the highest risk,” Whittemore added.

Other Stanford co-authors of the paper are statistician Joseph Rothstein, PhD, and senior research scientist Valerie McGuire, PhD.

The study was funded by the National Cancer Institute. Stanford’s Department of Health Research and Policy also supported the work.


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