The number of people with cancer is growing faster than the global population.
Yet a new study shows that it is far more complicated than the usual statistics suggest.
In an article published in the American Journal of Preventive Medicine, researchers from Boston University and Stanford University report that cancer growth in recent years is far higher than previously thought.
In the United States, the percentage of people living with cancer has grown from 14% in 2010 to 22% in 2019.
But in China, which is home to more than a third of the world’s cancer cases, the growth rate is more than double, to 31%.
This suggests that cancer is more complicated and more difficult to treat than previously assumed, the researchers say.
“We can say that, even if you are cancer free, your survival rate is still about 30% higher than the general population,” said Daniel M. Furlong, an assistant professor of preventive medicine and a member of the department of preventive science at Boston University.
“So, it’s a real problem that we don’t understand,” said Furlond, who was not involved in the research.
The new findings add to growing concerns about the increasing incidence of cancer in developed countries, where the burden of the disease is highest.
The growing trend may be a result of several factors, including the growing use of newer treatments, the rapid growth of genomic sequencing and the development of more precise, cost-effective drugs, Furlink said.
The researchers, led by David G. Hamer, professor of epidemiology and health policy at Stanford University, found that a number of factors are at play.
For one thing, people with pre-cancerous skin lesions may have more than one type of cancer, and may not be treated equally, which could contribute to increased rates of cancer.
A second factor is that patients with certain genetic conditions are at increased risk of developing cancer, but are more likely to be diagnosed early and treated effectively.
Finally, the disease can often be cured by other means, such as surgery.
A third factor is the growing availability of new treatments, including stem cells and other regenerative techniques, which are cheaper and easier to use.
But the researchers also found that some of these treatments can be harmful, even dangerous.
For example, in China the number of new cancer cases has increased by 60% over the past decade, according to figures from the National Health and Family Planning Commission.
China is now the only country in the world that has an excess of cancers, the study found.
China has more than 5 million new cancer patients, more than any other country, and more than 4 million people are under the age of 60.
Hamer and his colleagues looked at data from the World Health Organization’s cancer statistics for China from 2009 to 2019.
They looked at cancer cases in every province and included data on people living in hospitals and clinics, which was useful for tracking trends, but also to evaluate how cancer had been increasing.
In China, for example, the incidence of the most common cancers — skin, throat and stomach — increased by more than 10% over that period.
But for cancers in other organs, such a trend could not be observed.
In some cases, cancer rates fell because of improvements in treatment.
But other cases were actually growing.
For example, growth in liver cancers was nearly five times as fast in China as it was in the United Kingdom.
Other researchers have also looked at trends in cancer incidence in China.
But the study included data from China’s national statistics bureau and relied on publicly available government data.
The results also did not show an increase in cancers among the young, since many of the cancers were not considered new.
“The new data are interesting but not definitive,” said G. Anthony C. Basso, a professor of health policy and management at Boston College who was a co-author on the study.
Cancer-related costs are rising faster in the developing world than in the developed world, and the United Nations has warned of a growing risk of cancer-related pandemic.
For that reason, many countries are working on strategies to reduce the burden on their health systems.
For instance, Japan and the European Union have implemented public-private partnerships, in which private companies buy a share of the costs of a new cancer treatment.
The World Health Organisation also recently launched a campaign to combat cancer, with $10 million in funding announced this month for research into the cancer-prevention strategy.
But a similar initiative, launched in 2008 by the European Commission, has not been able to slow the rate of cancer growth, according a WHO statement.