Study: Cancer no longer rare in poorer countries
By Michael Coren
There were 10.9 million new cases of cancer worldwide and 6.7 million deaths in 2002.
Men and women in North America have the highest incidence of cancer worldwide.
The 1.6 million cancers in North America account for 14.5 percent of the world's total.
The most commonly diagnosed cancer worldwide was lung cancer, followed by breast and colorectal cancers, such as prostate cancer.
China has 20 percent of the world's total of new cancer cases (2.2 million cases)
Just over half of lung cancer cases -- 50.1 percent -- occur in developed countries, a significant change since 1980, when 69 percent were in developed countries.
(CNN) -- Poor countries have cancer rates much closer to those of rich nations, reversing a long-held belief among medical researchers, a study released Thursday reports.
"You're seeing some very interesting trends where cancer is no longer rare in the developing world," said Fadlo Khuri, a cancer researcher at Emory University's Winship Cancer Institute in Atlanta, Georgia, who reviewed the study by the International Agency for Research on Cancer.
Health officials once assumed that people in the developing world rarely lived long enough for many cancers to develop.
But the study, published in the American Cancer Society's journal, shows a different trend among cancer deaths.
More women in developing countries die of cancer than in the rich world, according to the study.
A greater percentage of men -- about 18 percent more -- still die of cancer in the rich world, but researchers said they expected a larger difference.
"In developing countries people are starting to live longer," said Otis Brawley, a cancer researcher at Emory.
"We may be looking at a simple biological principle that the older we get, we end up with more malignancies. ... Developing counties are also being exposed to the carcinogens that have been causing higher cancer rates in the industrialized world for 100 years."
According to the World Health Organization, life expectancies in the developing world's most populous countries, China and India, have lengthened considerably. In 1950, the average life expectancy was about 40 years old. By 2000, the figure had risen to 62.
The study also offers a disturbing trend for health officials concerned with smoking.
"One of the things that's most striking is that we continue to see lung cancer account for a disproportionate number of these deaths," said Khuri. "Lung cancer is one of the most poorly funded malignancies of all, in terms of therapeutic research. ...You're seeing an increase around the world and that suggests we need to redouble our efforts worldwide."
While industrialized countries have seen a decline in the number of lung cancers after massive anti-smoking campaigns, developing countries are experiencing the opposite trend. Developing countries' share of new lung cancer cases jumped from 31 percent in 1980 to almost 49.9 percent in 2002.
The World Health Organization, which calls tobacco "the world's most lethal consumer product," listed smoking as the world's second leading cause of death. One in 10 adults, about 5 million people, die from the habit each year, a growing number of whom live in developing countries.
Although lung cancer is still more common in Eastern Europe and North America, this is changing as tobacco companies focus billion-dollar publicity campaigns on emerging markets such as China with 1.3 billion people.
"That's frightening and, frankly, it scares the hell out me," said Brawley. "We're going to have an epidemic of lung cancer in China if we don't have one already."
Rich, poor nations
There also were significant findings in how cancer is distributed around the globe.
The study found that people in rich countries tended to have cancers linked to affluence or a "Western lifestyle" -- cancers of the colon, rectum, breast and prostate -- that can be caused by obesity, lack of exercise, diet and age.
"We use our bodies longer with fatty diets," said Khuri of people in industrialized nations.
In the developing world, cancers of the liver, stomach and esophagus were more common, often linked to consumption of carcinogenic preserved foods, such as smoked or salted food, and parasitic infections that attack organs.
As a whole, the world saw 10.9 million new cases of cancer in 2002, the study found. There also were more survivors of cancer in 2002, more than 24 million, living at least five years after their diagnosis than ever before.
The most lethal cancers were lung, stomach and liver cancers, accounting for 37 percent of the 6.7 million cancer deaths in 2002.
The most diagnosed worldwide were lung cancer, with 1.35 million cases, followed by breast and colorectal cancers, such as prostate cancer.
Lung cancer accounted for about 12 percent of all new cancer cases and 1.2 million deaths.
Breast cancer was the most common cancer among women and had one of the best survival rates -- the average in developed countries is 73 percent and in developing countries 57 percent.
The most intractable malignancies such as liver and lung cancer yielded little to modern treatments.
In the developing world, 8.9 percent of those diagnosed with lung cancer lived an additional five years. In the United States, where advanced chemical and radiological treatments are available, only 15 percent of lung cancer patients survived. Europe showed a similar survival rate of about 10 percent.