Can precision medicine be applied to disease prevention? That was the question at the center of the 163rdCutter Lecture on Preventive Medicine, at Harvard T.H. Chan School of Public Health on May 6, 2016. Speaking to a packed auditorium in Kresge G-1, Duncan C. Thomas, Professor and Director of the Biostatistics Division at the University of Southern California, said that personalized prevention could work in the right circumstances.

In 2015, President Obama launched his Precision Medicine Initiative (PMI), earmarking $215 million to help researchers, providers, and patients work together to develop individualized care. So far, much of the focus of the PMI has been on treatment—finding ways to tailor treatment to a person’s unique biological and genetic needs. Thomas said it’s worth investigating whether the same principles can be applied to prevention.

He said that when considering targeted methods of preventions, scientists and doctors must ask a series of questions: Does an effective intervention exist? Will it change outcomes? Would prevention be improved by targeting high risk individuals, and can those people be identified? Is the intervention more effective in one risk group versus another?

Thomas talked about these questions in the context of targeted screening for colorectal cancer. He pointed to data showing that since 1975 there has been a 45% decrease in colorectal cancer incidence and mortality in the U.S., noting that decline can be partly attributed to better cancer treatment, but also to more effective screening practices—such as earlier detection of symptomatic cases. If increased screening does help reduce cases of colorectal cancer, then it may open the door to more precise approaches—such as using a person’s family history or genetic markers to develop more targeted screening techniques, he said.

But there are some potential downsides to this kind of approach, said Thomas. For example, colonoscopies can be uncomfortable and expensive.

“The question is, are those differences [in incidence and mortality risk] worth the additional cost and complexity,” he said. And ultimately the question he says is, “Will lives be saved?” Thomas says that personalized prevention is a nice idea, but that more research is needed before it can be effectively implemented.