Cancer doesn’t discriminate. It’s a leading cause of death across the world and across all income levels, according to a recent study on the global cancer burden from the American Cancer Society. And from a global perspective, the death toll is only expected to increase in the coming years.
But there’s some good news, too. The study, which was published in Cancer Epidemiology, Biomarkers & Prevention in December, shows that mortality rates for some cancers are on the decline. (See “Key Findings” box.)
We sat down with the study’s lead investigator Lindsey Torre, MSPH, an epidemiologist in the surveillance research group at the American Cancer Society, to learn more about her findings on the global cancer burden.
Q: The study is titled, “Global Cancer Incidence and Mortality Rates and Trends – an Update.” What is it an update to, and what are some of the new insights?
A: This is an update of the 2010 paper written by our group, “Global patterns of cancer incidence and mortality rates and trends.” Unfortunately, we found that some of the disturbing trends documented in the 2010 paper, such as increasing cancer rates in developing countries, have continued.
Q: Lung, breast, and colorectal cancers are on the rise in many low- and middle-income countries. What’s driving the trend, and how can it be slowed in places where there aren’t ample economic resources?
A: These are commonly thought of as cancers of Western countries because they are associated with lifestyle behaviors related to urbanization that have been particularly increasing in low- and middle-income countries. For example, increasing lung cancer is primarily caused by historic increases in smoking because of the global spread of the tobacco epidemic. Colorectal cancer rates are rising because of the obesity epidemic. Reasons for increasing breast cancer rates in these countries are thought to be related to changing reproductive patterns, such as later age at childbirth and having fewer children, which increases breast cancer risk.
One of the primary measures countries can take, even those with lower resources, is tobacco control. Smoking is the cause of the most preventable deaths in the world. And there are several proven tobacco control measures which can help people quit smoking and avoid smoking initiation, such as counter-advertising, smoke-free environments, cessation assistance, and most importantly, taxation.
Q: When it comes to the most commonly diagnosed cancers, there seems to be more variation across countries among men than in women. Why do you think that is?
A: That’s a great question. Much of the answer relates to the interplay between economic transition and cancer risk factors. In much of the world, breast cancer has overtaken cervical cancer as the most common cancer in women because of increasing breast cancer rates, as we discussed earlier, accompanied by declines in cervical cancer because of prevention through screening. Among males, two commonly diagnosed cancers are lung cancer, which is caused by smoking, and prostate cancer, whose high incidence in many countries largely reflects the use of prostate-specific antigen (PSA) testing. But other cancers are most common in countries where the tobacco epidemic doesn’t dominate and where PSA testing is less common. In India and Pakistan, for example, lip and oral cavity cancer is most commonly diagnosed in males due to the use of smokeless tobacco products.
Q: Were there any surprising findings?
A: What might surprise many people is the fact that cancer is not a disease of only developed countries. While the burden in those countries is substantial, it is also considerable and growing in developing countries. These countries already have an excess of infection-related cancers, such as stomach, liver, and cervix, in addition to rising rates of cancers such as lung, colorectum, breast, and prostate.
Q: What would it take for the next global cancer update to include more good news?
A: A substantial portion of cancers could be prevented using known measures such as tobacco control, vaccination (HPV, hepatitis B), and early detection tests (breast, cervix, colorectal). We’re already making major strides in cervical cancer prevention, and not just in high-income countries. The HPV vaccine is available and cost barriers are being overcome to introduce it in low- and middle-income countries; however, we won’t see the effects of this health intervention for many decades to come. More screening initiatives are also underway to detect and remove precancerous lesions or catch cervical cancer early, when it is most treatable.
Also, the burden of suffering can be reduced through appropriate treatment and palliative care. For example, many people with cancer, especially in low- and middle-income countries, suffer needlessly because pain medications are not available to them. Initiatives like the American Cancer Society’s Treat the Pain program are working to improve access to opioid analgesics for pain management.