Teens are heeding the message to stay away from cocaine and cigarettes, but when it comes to marijuana not so much.
An annual survey by the National Institute on drug use found 60% of high school seniors don't think regular pot use harmful to their health.
More than a 1/3 of them admitted to using it within the past 12 months.
Nearly 7% say they smoke marijuana daily.
That's nearly triple from what it was 20 years ago.
Researchers say going forward they'll explore the link between teen's drug use and states that allow the use of medical marijuana.
New data from the World Health Organization show a sharp increase in the number of cancer cases worldwide.
14 million people were diagnosed with cancer in 2012, compared with 12.7 million in 2008.
The number of cancer deaths also rose. One of the most notable increases was seen in breast cancer cases and related deaths.
Experts blame lifestyle factors in part poor diets, little exercise and smoking.