Prevention Is Crucial to Stem 'Tidal Wave of Cancer'

Zosia Chustecka

February 04, 2014

Prevention of cancer is key, say experts speaking out today on World Cancer Day.

Cancer as a single entity is now the world's leading cause of death, with 8.2 million deaths a year, according to the Union for International Cancer Control.

Dr. Bernard Stewart

Prevention has a crucial role to play in stemming the "tidal wave of cancer that we are facing," said Dr. Bernard Stewart, from the University of New South Wales in Sydney, and coeditor of the World Cancer Report 2014, issued by the International Agency for Research on Cancer (IARC).

"It's untenable to think that we can treat our way out of the cancer problem.... More commitment to prevention and early detection is desperately needed in order to complement improved treatments and address the alarming rise in cancer burden globally," said Christopher Wild, MD, director of the IARC and coeditor of the new report.

We also have a duty of care for the populations of tomorrow. Dr. Christopher Wild

Speaking at a press briefing in London, Dr. Wild said that he has been working in cancer research for more than 30 years, and when people hear that, the first thing they always ask is, "Have you found the cure yet?" Nobody ever asks about prevention, and yet this is key, he said.

"We clearly have a duty of care for the patients of today, with an emphasis on high-quality treatment," he said, "but we also have a duty of care for the populations of tomorrow, implementing the knowledge that we have, focusing on prevention and early detection of cancer, which is a necessary complement to the advances in treatment."

Half of All Cancers Could Be Prevented

Dr. Christopher Wild

"About half of the cancers could be prevented by applying the knowledge that we currently have," Dr. Wild said.

Top of the list is tobacco control, which is thought to cause about 20% of all cancers globally. This includes taxation and restrictions on advertising and smoking in public places — a "legislation approach combined with a change in human behavior," Dr. Wild commented. "This is a lesson that we need to take into other areas of cancer prevention as we move forward," he suggested.

Next on the list are infections, estimated to cause some 16% of cancers worldwide. These include hepatitis B virus (HBV) and liver cancer, human papillomavirus (HPV) and cervical cancer, and Helicobacter pylori and stomach cancer.

All 3 of these cancers are huge problems on a worldwide scale. Liver and stomach cancer are the second and third top cancer killers (after lung cancer), globally, accounting for the highest mortality rates. This is partly because of poor survival rates, but also because these cancers are particularly common in the less developed regions of the world, Dr. Wild commented.

Cervical cancer is the second most common cancer in women worldwide (after breast cancer), and it is still common in sub-Sahara Africa and in areas of South America and Southeast Asia. And yet this is a cancer for which there are very efficient early detection systems (including a cheap detection method based on vinegar) and for which there is a vaccine, Dr. Wild noted.

Next on the cancer prevention list are alcohol, physical inactivity, and being overweight/obese. In these cases, the way forward is less clear. "Here we still need research on how best to reverse these trends," Dr. Wild commented.

The list continues with radiation exposure, which includes excessive sunlight and excessive use of medical diagnostic procedures such as CAT scans, particularly in children. There are also environment factors, which include air pollution, occupational exposure, and reproduction/hormonal factors in women, such as number of children and length of breast-feeding.

Prevention works, but it takes time. Dr. Christopher Wild

"Prevention works, but it takes time," Dr. Wild said. He illustrated this point with 2 examples: lung cancer rates falling after a decrease in cigarette consumption, seen over a period of 20 to 30 years; and cervical cancer rates falling after screening was introduced, which was very marked in Finland in particular, but this was over a period of 40 to 50 years. "Prevention does work, but it needs a long-term political commitment," he concluded.

Each Country Must Set its Own Priorities

Although the cancer burden is discussed globally in the report, it also breaks out the problem into various regions of the world, as different regions have different cancers as their most pressing problems.

"Countries need to look at their own particular situation in order to implement their own priorities of cancer control," he said.

To illustrate the point, he highlighted sub-Saharan Africa, where 1 in 3 cancers is associated with a chronic infection, which makes vaccination against HBV and HPV a real priority here, he said.

In contrast, only about 1 in 7 cancers is associated with infection in Europe, while in Australia that drops down even further to 1 in 30. However, Australia has its own particular cancer problem — that of melanoma — which results from the "Aussie lifestyle of lying on golden sands until you are cooked evenly on both side," commented Dr. Stewart.

Moving Toward a Systematic Approach

"What is new now, in 2014, is that prevention has moved from a naive approach of passing out pamphlets and haranguing people about stopping smoking to a more systematic approach," Dr. Stewart commented.

This systematic approach is exemplified by the World Health Organization Treaty on Tobacco Control, which emphasizes a spectrum of legislation on advertising, availability, pricing, etc., which empowers countries to apply these measures to stop the ill health associated with smoking, he said. Australia is one of the leaders in the world in this field, with very strict controls on advertising and the first to introduce plain packing despite legal action from the tobacco industry.

The example of tobacco control shows how it can be done, Dr. Stewart suggested, adding that these steps have altered the "conventional consciousness" about smoking.

"We can now apply some of these principles to lifestyle factors that are known causes of cancer in our society," he said. These include largely, but not exclusively, drinking alcohol, a lack of exercise, and overweight/obesity, which is fast becoming an epidemic.

How to go about prevention in these cases is not entirely clear, however. "The evidence for obesity and physical inactivity is quite strong, but it is not clear how to turn this information into particular strategies," Dr. Stewart commented.

The IARC and the World Cancer Report are not making suggestions on how to go about it, Dr. Stewart emphasized. The role of the agency is to provide evidence and to "open the debate."

Some of the debate is focused on labeling and pricing, he noted, but there are subtleties here that it can be difficult to explain to the general public. For example, cans of soft drink cannot be labeled as causing cancer, even though it is recognized that drinking sweetened drinks contributes to obesity, which increases the risk for cancer.

Public Awareness Is Low

This issue of public awareness of how everyday behaviors can influence cancer risk is emphasized by the American Institute for Cancer Research (AICR). Focusing on the United States, this agency emphasizes that about one third of all cancer could be prevented by making changes to diet, weight, and physical activity.

However, awareness of this among the general public is low. The AICR released results from an online survey of 1233 adults conducted in December 2013, which it says was weighted and found to be representative of all American adults over 18 years of age.

The survey found that 17% of adults agreed with the statement that "people can't do anything to change their risk of getting cancer."

Just over half (58%) of the adults surveyed were aware that diet can affect the risk for cancer, but a lower proportion (41%) knew that body weight has an impact, and 20% of adults disagreed, and thought that body weight had no influence on cancer risk.

Lowest awareness was found for the link between cancer with exercise. Only 39% of adults agreed with the statement, "how active someone is affects their risk of getting cancer," while 23% of adults (nearly 1 in 4) disagreed.

The survey "tells us that there are millions of Americans who don't yet have the information they need," commented Alice Bender, MS, RD, associate director for nutrition programs at the AICR. They have not yet heard "the empowering message that they can take steps to protect themselves."

The ACIR aims to increase awareness with its Cancer Prevention: Do Something campaign, which is summarized as, "Eat well, move more, stay lean," and adds, almost as an afterthought "and of course, don't smoke."


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