More than 200,000 people could be saved from experiencing cancer in the next 25 years if all Australians maintained a healthy weight and exercised enough.
That includes 190,500 potentially preventable cancers linked to Australian's being overweight and another 19,200 connected to people not exercising for at least five hours a week.
The figures have emerged in new research by the Brisbane-based QIMR Berghofer Medical Research Institute, published in the International Journal of Cancer on Monday.
The results of the study, funded by the Cancer Council and the federal government's National Health and Medical Research Council, come as more than two-thirds of adults are considered overweight or obese.
Nearly half of Australians aren't sufficiently active.
The cancers with the highest number of potentially avoidable cases include post-menopausal breast, endometrium, bowel and kidney cancers.
Obesity Policy Coalition executive director Jane Martin says the number of deaths that could be stopped through healthier lifestyles is striking and shows Australia has got a "very serious problem".
"There are a proportion of cancers that aren't preventable, but this shows that there are a lot that are," she told AAP.
"We need to do some broad policy changes to create an environment that makes the healthy choice the easy choice."
Restricting junk food marketing to children, putting a health levy on sugary drinks and improving food labelling are among initiatives Ms Martin's group believe could help.
They also recommend funding more effective social marketing campaigns encouraging people to be a healthy weight.
Cancer Council chief executive Sanchia Aranda said both sides of politics need to recognise their responsibility to promote more public education about the benefits of good nutrition and exercise.
But individuals can also take steps to reduce their risk of lifestyle-related cancers, she said.
"Improving your diet can be as simple as eating more fruit, vegetables and whole grains. An easy measure is the two-and-five goal - two fruits and five serves of vegetables every day," she said.
"When it comes to physical activity, if you can't commit to five hours of physical activity per week it's important to remember that every little bit counts.
"So making an effort to be more active each day can still lead to better health."
