Half of all cancer is preventable based on what we already know, including modifiable causes of the disease such as obesity, physical inactivity and the one-third of cancers blamed on tobacco.
"We could prevent more than 70 percent of cancer caused by smoking in the United States - lung cancer, bladder cancer, kidney cancer, head and neck cancer - all from smoking," says Washington University professor Graham Colditz. "Others on the list as well."
Colditz, associate director at the Siteman Cancer Center in Saint Louis, writes about improving cancer prevention in the journal Science Translational Medicine.
He and his colleagues came up with that estimate by projecting the situation in the state with the lowest cancer rate in the country.
Colditz based his analysis on data from a variety of studies in the United States, but he says cancer prevention is just as important in other countries, even if their strategies may differ.
So, while smoking is also a big target in low and middle income countries, he notes that so, too, are the infections often linked to cancer.
"Liver cancer from hepatitis, cervical cancer from the HPV [human papilloma] virus. So the infectious origins account for a bigger percentage of cancer in those settings."
For a variety of reasons, Colditz says cancer research is overwhelmingly focused on treatment. "The reality is that if we could shift just a fraction of the research to prevention, we'd have a major payoff for society."
But it's not just medical professionals who have a role to play.
What we eat, how much we exercise, our environment at work - these are among the factors that can affect our health in general, and the risk of cancer in particular. Lawmakers, Colditz says, can regulate exposure to cancer-causing substances.
"We need the whole of our society to accept the responsibility and the strategies to maintain a healthy lifestyle and avoid cancer."
