Though there have been huge advances in cancer treatment and prevention in recent decades, the disease is still poised to become the leading cause of death worldwide, experts say.
That's because people in developed countries are living longer and obesity rates are continuing to rise. And while smoking rates are falling in most industrialized countries, rates are rising in other parts of the world.
In a cancer-themed edition of JAMA, the Journal of the American Medical Association, American Cancer Society epidemiologist Susan Gapstur offers a commentary about the fight against cancer.
She notes that while progress is being made in some aspects of cancer, worrying new trends are threatening to override those gains.
In the U.S. for example, the death rate from cancer has fallen by nearly 16 per cent in 20 years. But the disease will soon edge out heart disease to become the most deadly disease worldwide.
Part of the reason is that people are living longer, and age is a top risk factor for many types of cancer, including prostate and breast cancer.
As life expectancy increases, the lifetime risk of being diagnosed with cancer increases as well, so that nearly one in two American men and more than one in three women can now expected to be diagnosed with cancer in their lifetimes.
Many of these cancers, such as liver, brain, ovarian and lung cancer, are highly lethal and few treatments exist.
Yet some advances have come in recent years. Lung cancer rates, for example, are falling, due mostly to stop-smoking campaigns and anti-smoking legislation.
"Nearly 40 per cent of the reduction in the overall cancer death rate in men between 1990 and 2006 was related to the decline in tobacco use," Gapstur told reporters Tuesday afternoon.
Other advances have also helped. The Pap test, for example, has dramatically reduced cervical cancer death rates; mammography and colon cancer screening have been shown to save lives; and progress has been made in effectively treating childhood cancers, testicular cancer, and other cancer types.
But now there's concern that obesity may cancel out many of the recent life expectancy gains. Research shows that about one third of cancer deaths expected every year are related to nutrition, overweight or obesity, and physical inactivity. These factors have been shown to have clear links to colorectal cancers, breast cancer and kidney cancer, among other forms.
"Avoiding overweight and obesity is going to be critical for keeping our progress going forward in this battle against cancer," she said.
As well, smoking rates are still high in many parts of the world, causing Gapstur to predict a "worldwide cancer epidemic" that will help cancer overtake heart disease "as the number one cause of mortality in the world this year."
Gapstur and her co-authors write that though the challenges of fighting cancer may be daunting, the tools doctors now have are also growing more sophisticated.
"It has become clear that no single silver bullet or therapeutic arsenal will win this war. Instead, it is essential to move forward on multiple fronts simultaneously, addressing the entire spectrum, from primary prevention to early detection, treatment, and palliation," they write.
"Although progress has been made in reducing cancer mortality rates, the number of persons affected by cancer will increase due to an aging population unless progress in cancer prevention and reducing incidence rates are accelerated."
