About 37,000 Australian cancer cases could be prevented each year, the majority just through six lifestyle changes.
That translates into one in three cancers, according to the first national study of incidence of the disease and preventable causes.
Funded by Cancer Council Australia and carried out by QIMR Berghofer Medical Research Institute, the study identified 13 risk factors with 24 cancer types.
"We always understood these were associated with cancer, but we've never been able to quantify them other than with tobacco," the council's CEO Professor Sanchia Aranda told AAP.
The six risk factors causing about 90 per cent of preventable cancers are smoking, UV radiation, alcohol, poor diet, being overweight and physically inactive.
Diet includes too much red and processed meat and not enough fibre, fruit and vegetables.
"This is a call to action, to say you can take charge of your future health," Prof Aranda said.
"When you talk to the community, they say `but everything causes you cancer so what's the point?'.
"But, in fact, 37,000 cancers are preventable, not by weird things people talk about but mostly by the things we already know like smoking and too much sun.
"Stop worrying about the little things and being complacent about the idea that everything causes cancer."
People often thought tobacco was only associated with lung or possibly oral cancers, but the study showed links to other cancers including 951 cases of bowel cancer in 2010, and 781 to bladder cancer.
"People also may be surprised at the relationship between being overweight and cancer," she said.
"We are an increasingly overweight population, yet there are nearly almost 4000 cancers a year that could be avoided if we could get thinner."
THE MOST PREVENTABLE CANCERS
* Lung, cases would be cut by 8569 yearly through changing lifestyle;
* Colorectal (bowel), 7404
* Melanoma, 7220
* Breast, 3233.
