Cancer rates could be reduced by 40 percent with healthy nutrition and exercise, and quitting smoking, Professor Jim Mann, co-author of the World Cancer Research Fund Report said.
But "we need to move a bit faster before our health system falls apart" due to the load, he said at a symposium at Te Papa last week.
The report, published in November, judged that, "avoidance of tobacco in any form, together with appropriate food and nutrition, physical activity and body composition, have the potential over time to reduce much and perhaps most of the global burden of cancer."
The report cost NZ$21.7million and is said to be the most authoritative global report on food, nutrition and cancer.
University of Otago Wellington senior research fellow Dr Caroline Shaw said, "To have any chance of achieving the goals of the World Cancer Research Fund Report, dramatic changes in New Zealand society need to occur.
"We need to stop unhealthy food being advertised at all the times that children watch TV; increase the price of unhealthy foods (such as sugary drinks) and lower the price of healthy food; we need paid maternity leave for six months to help women breastfeed; and to force local government to prioritise walking, cycling and public transport – not building more roads."
10 Recommendations from World Cancer Research Fund Report
1. Be as lean as possible without becoming underweight
2. Be physically active for at least 30 minutes every day
3. Avoid sugary drinks. Limit consumption of energy-dense foods (particularly processed foods high in added sugar, or low in fibre, or high in fat)
4. Eat more of a variety of vegetables, fruits, wholegrains and pulses such as beans
5. Limit consumption of red meats (such as beef, pork and lamb) and avoid processed meats
6. If consumed at all, limit alcoholic drinks to 2 for men and 1 for women a day
7. Limit consumption of salty foods and food processed with salt (sodium)
8. Don't use supplements to protect against cancer
9. It's best for mothers to breastfeed exclusively for up to 6 months and then add other liquids and foods
10. After treatment, cancer survivors should follow the recommendations for cancer prevention
And, always remember – do not smoke or chew tobacco
The recommendations in the report were challenging and the current environment we live in promotes "poor nutrition, low levels of physical activity and obesity – this is reflected in the fact that half of New Zealand's adults are overweight or obese, she said in a press release.
Fatness Means Cancer Risk Higher
The more body fat a person has, the higher the risk of developing bowel cancer and breast cancer (post menopausal), the report said.
Pancreatic cancer and endometrium cancer risk also increase with increased body fat.
Professor Mann said the fat around a person's abdomen is "particularly important" in reducing cancer risk, as well as diabetes and cardiovascular risks.
In comparing waist circumference and bowel cancer, "for every inch increase there was an increase in risk," Professor Mann said.
He strongly advised that Maori and Pacific Islanders not to be given a higher acceptable amount of body fat.
"For goodness sake, don't do that."
Sedentary behaviour significantly increased the risk of cancer, along with consuming energy-dense foods, fast foods, sugary drinks, and watching TV, the report said.
The most convincing evidence to reduce cancer risk through obesity was to undertake physical activity; while eating low energy-dense foods and being breastfed also decreased the risk of developing cancer later in life.
Physical Activity, Obesity and Climate Change
Solutions to climate change and obesity could go hand-in-hand, suggested Associate Professor Grant Schofield of Auckland's AUT University at the Cancer Society symposium.
"It's hard to imagine a sustainable society that doesn't have high levels of physical activity and healthy eating. It's hard to imagine a community that is carbon neutral, where fruit and produce are not grown locally, and people are not walking and being social."
He said Auckland is now on par with Los Angeles for the number of cars owned per capita, the second greatest number in the world.
The evidence that suggests physical activity decreases cancer risk is "convincing" for colon cancer and "probable" for breast cancer (post-menopausal) and endometrium cancer, Professor Schofield said.
Half of New Zealanders are "insufficiently active" and 6-12 percent are sedentary, he said.
"Limiting sedentary behaviour is important, it seems to be a problem."
New Zealanders watch more than three hours of TV a day on average, but the number one reason for not exercising is lack of time, he said.
The Push Play message from SPARC recommends people do at least 30 minutes of moderate activity per day, the same message the report is pushing.
Professor Schofield said there are four main areas people could look at increasing physical activity as a part of everyday life, including occupation, leisure time, travel, and home duty.
For some though, obesity can be an occupational hazard. The average weight gain for bus drivers in first six months is 8kg.
A study of 1200 Auckland school children showed increased leisure time actually resulted in less physical activity.
The children were given pedometers to record their steps and the results showed they walked 30 percent less steps on weekends – a surprise for Professor Schofield who thought the opposite would be true.
He said the Green Prescription and Active Families programmes were successful in increasing activity levels in our communities and the involvement of Doctors was an important step towards achieving this.
Healthy food must also be the easiest and cheapest choice for consumers, he said.
Reversing Cancer
Healthy nutrition, exercise and quitting smoking can not only reduce rates of cancer occurring, but can contribute to the reversal of the disease, Professor Lynne Ferguson from Auckland's Cancer Society said.
"It is possible to halt or sometimes reverse the cancer process."
Professor Ferguson spoke about the relationship between cancer and nutrition at the Wellington symposium.
There must be buy-in from the public to improve nutrition, she said.
"Telling people what not to do doesn't work."
She said there was a general consensus that increasing dietary fibre will decrease cancer risk, but warned that cereals must be stored properly.
"Evidence shows that vegetables, fruits and other foods containing dietary fibre (such as wholegrains and pulses) may protect against a range of cancers including mouth, stomach and bowel cancer. They also help to protect against weight gain and obesity," states the report.
Red meat and processed meat are linked strongly with bowel cancer, and "there is no amount of processed meat that can be confidently shown not to increase risk," the report said.
The risk of red meat contributing to cancer can be "very substantially reduced" by adding greens, onion, and spices to meat patties, Professor Ferguson said. "You'll find a significant difference."
She said the evidence showed a stronger cancer risk with processed meat than red meat, but a lot of European data was used in the study, where "high amounts of salamis and processed meats were eaten on high occasion".
"Green-yellow veges are likely to prevent stomach cancer."
The report recommends reducing consumption of energy-dense foods, sugary drinks, and fast foods. She said the single biggest avoidable cause of cancer is still cigarette smoking. Ms Ferguson was one of four New Zealand peer reviewers for the report.
The report took six years to produce and looked at all available research on cancer prevention. An initial 500,000 studies were screened down to 22,000, and then it was decided that 7,000 of these studies met the rigorous standards for inclusion in the report.
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