A world expert, professor Graham Colditz, an Australian who has taught Harvard, and is now based at the University of Washington Medical School, warns that Australia could expect a double in the number of cancer cases within 20 years, if poor lifestyle habits are not changed.

In Australia, obesity and excess weight alone costs a whopping $21 billion per year, based on the study published in the recent issue of the Medical Journal of Australia, says Professor Colditz. He adds that cancer-related deaths could be easily prevented if we did not gain unhealthy weight through our adult years.

On a bright side, he says that half of the cancers are preventable and with continuous changes in lifestyle habits, the number would increase.

Professor Colditz calls for a holistic method to preventing cancers and other diseases, by looking at the way people work, what they do at home, the way they work, the schools, adult education institutions, community groups, urban planning and design and the delivery of health services.

Diet and exercise are not just vital to cancer prevention, but also included in the supportive treatments for cancer patients. He says that a more holistic way would be to have oncologists to discuss them when they treat patients.

An oncologist is focused on the patient's cancer but perhaps they need to look past the cancer to the whole person to discuss diet and exercise, says Prof Colditz.

Since solid improvements have been made through the banning of smoking in workplaces, hospitality venues, transport and other public places, he says now is the time, to extend the focus of healthy eating and exercise.

He adds, Physical fitness and weight control helps reduce the reoccurrence of cancer and improve and extend survival rates too.

Obesity is a serious problem with one in four Australian children already obese or overweight, says Kathy Chapman, the Director of Health Strategies at Cancer Council NSW.

We cannot allow this epidemic to worsen. Our message is that you don't have to make massive lifestyle changes to reduce your risk of developing cancer. Even small things, like getting off the bus stop early and walking the rest of the way, can result in big benefits to your health.

Visit www.cancercouncil.com.au for more cancer prevention details or call the Cancer Council Helpline at 13 11 20.