Cancer Burden on the Rise in Much of the World

Pam Harrison

June 11, 2018

The incidence of cancer has increased worldwide during the past decade, but at least some of that increase is in lung, colorectal, and skin cancer, which are potentially preventable, the Global Burden of Disease (GBD) study indicates.

"While the increase in lung, colorectal and skin cancers over the past decade is concerning, the prevention potential is substantial," Christina Fitzmaurice, MD, MPH, assistant professor of global health, Institute for Health Metrics and Evaluation at the University of Washington, in Seattle, said in a statement.

"Vital prevention efforts such as tobacco control, dietary interventions, and broader health promotion campaigns need to be scaled up in response to this rise in lifestyle-related cancers," she added.

The study was published online June 2 in JAMA Oncology.

The systematic analysis of the GBD study included 29 cancer groups for which the incidence, mortality, and disability-adjusted life-years (DALYs) were evaluated for 195 countries and territories between 2006 and 2016.

"Cancer cases increased by 28% between 2006 and 2016," the investigators report, adding that the largest increases occurred in the least developed countries.

In 2016, 17.2 million people worldwide were diagnosed with some form of cancer, and 8.9 million died of cancer in the same year.

Cancer also caused 213.2 million DALYs in the same year, virtually all of them from years of life lost.

"Globally, the odds of developing cancer during a lifetime (age 0 - 79 years) differed by sex," the authors continue.

The odds of developing cancer were 1 in 3 for men, compared to 1 in 5 for women, although these odds differed substantially among the different sociodemographic index (SDI) quintiles.

For example, cancer risk went from a low of 1 in 8 in the lowest SDI quintile for both men and women to 1 in 2 in the highest SDI quintile for men and 1 in 3 in the highest SDI quintile for women.

Countries with a high SDI have high levels of income and education and low levels of fertility, whereas low SDI countries have low levels of income and education and high levels of fertility.

"In 2016, prostate, TBL (tracheal, bronchus and lung), and colorectal cancer were the most common incident cancers in men — accounting for 40% of all cancer cases," the researchers report.

Lung cancer was the leading cause of cancer-related death in men worldwide as well as the leading cause of cancer mortality globally, accounting for almost 20% of all cancer-related deaths in 2016, the investigators point out.

For women, the most common cancers were breast cancer, colorectal cancer, and nonmelanoma skin cancer, which made up 40% of all cancer cases among women in 2016.

Between 2006 and 2016, age-standardized annual incidence rates for all cancers increased on average in 130 of the 195 countries examined.

On the other hand, age-standardized annual death rates from all cancers on average decreased in 143 of the 195 countries examined, the exceptions being largely in Africa and the Middle East, where annual death rates from cancer did not decline.

Across the decade, middle SDI countries experienced the largest increase in cancer incidence rates, at 38%; the largest proportion of this increase was attributed to age.

Indeed, in both high-middle SDI and high-income countries, increases in cancer incidence were mainly due to an aging population, the investigators point out.

Vast Heterogeneity

Investigators also note that there was "vast heterogeneity" in the incidence, mortality, and DALYs from cancer between low- and high-SDI countries.

For example, women in low-SDI countries were almost four times more likely to develop cervical cancer compared to women in high-SDI countries.

There was also significant variability in the incidence of stomach and liver cancer across different SDI countries, although rates of both cervical and stomach cancer have fallen in all SDI quintiles during the past decade, the study authors note.

Conversely, both the incidence and death rates from cancer were higher in high-SDI countries in 2016 than they were in low-SDI countries.

For example, the risk of developing breast cancer over a lifetime was highest, at 1 in 10, for women in high-SDI countries, compared to only 1 in 50 for women in low-SDI countries.

"Since even in the best-case scenario only a fraction of cancers are preventable under current conditions, providing universal access to health care is crucial for cancer control," the investigators observe.

"Improving access to advanced diagnostic technologies not commonly available in low SDI countries is a critical step toward achieving health equity globally," Fitzmaurice added in a statement.

The Institute for Health Metrics and Evaluation received funding from the Bill & Melinda Gates Foundation. The authors have disclosed no relevant financial relationships.

JAMA Oncol. Published online June 2, 2018. Full text

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