Close to half of cancer deaths preventable, report says

Close to half the world’s 10 million yearly cancer deaths can be prevented by tackling risks like tobacco and alcohol use, excess body fat and exposure to environmental pollutants, according to a report released Wednesday.

The Cancer Atlas, a joint project of the American Cancer Society and the World Health Organization’s International Agency for Research on Cancer, draws on dozens of academic studies to present an overview of how cancer risks and methods of control are evolving over time across the world.

Much of the Atlas focuses on cancer risks that are "modifiable" — that is, potentially preventable or at least susceptible to mitigation by changes in human behavior.

"Tobacco, alcohol consumption, excess body weight, UV or harmful sun exposure — there are public policies that can modify the risk factors," said Dr. Ahmedin Jemal, senior vice president of surveillance and health equity science at the American Cancer Society and lead editor of the report. "The only issue we have had, really, is we don’t have this commitment from public leaders to implement these public policies across the world."

Primary prevention and screening are "low-hanging fruit," Jemal said.

Dr. Paolo Boffetta, associate director for population sciences at Stony Brook Cancer Center, who was not involved in the new report, said its systematic approach could be a useful starting point for advocates and policymakers. But they will need to drill down "to understand exactly what’s going on with specific populations," he said.

Some incidence of cancer in a society is inevitable, a function of "more and more people getting more or less healthily to old age" instead of dying earlier from unrelated diseases or other causes, Boffetta said.

Some risk modifications are unambiguously good. It’s possible, for example, to imagine a world without smoking, which kills millions of people every year more than half a century after scientists started teasing out the epidemiology of lung cancer, he said.

Some modifications aren’t so clean cut. "Think about having children at a later age," Boffetta said. "Having fewer children is a risk factor for breast cancer," a phenomenon that’s been observed in places like India, China and Pakistan. But that phenomenon is "part of a change in the role that women have in those societies," he said. "What’s better — for women to stay at home, have their first child at 18 and have eight children, or go to school and work and have their first child when they’re 30?"

In North America, the report found, incidence was highest for cancers associated with behavioral factors like smoking and excess body weight. The most common cancers were breast, lung, prostate and colorectal. In the United States, the mortality rate has declined 34% since 1991, but the ACS still projects more than 600,000 cancer deaths and 2 million cancer diagnoses this year. 

Globally, 19 million people are diagnosed annually with cancer, a number that, without intervention, could rise to over 33 million cases and 18 million deaths by 2050, driven by population aging and growth.