Cancer leading cause of death in high-income countries, study finds

By Nina Massey, PA Science Correspondent

Cancer is now the leading cause of death in high-income countries, while cardiovascular disease continues to be the biggest killer in poorer nations.

Deaths from cancer in the richer countries have become twice as frequent as those from cardiovascular disease, scientists say.

In a pattern observed for all causes of death except cancer, overall mortality per 1,000 person-years was lowest in high-income countries at 3.4%, intermediate in middle-income countries at 6.9%, and highest in low-income countries at 13.3%.

Cardiovascular disease was the most common cause overall at 40%.

But that ranged from only 23% per cent in high-income countries (HIC) to 41% in middle-income countries (MIC) and 43% in low-income countries (LIC).

Cancer was the second most frequent cause of death at 26% of deaths, but this proportion varied and was responsible for the majority (55%) of deaths in HIC, 30% in MIC and 15% in LIC.

Person-years is a measurement that takes into account both the number of people in a study and the amount of time each spends in the study.

Looking at data in this way can reveal trends and allows researchers to communicate levels of risk.

Professor Salim Yusuf, principal investigator of the study, said: "The fact that cancer deaths are now twice as frequent as CVD deaths in high-income countries indicates a transition in the predominant causes of death in middle age.

"As CVD declines in many countries because of prevention and treatment, cancer mortality will likely become the leading cause of death globally in the future.

"The high mortality in poorer countries is not due to a higher burden of risk factors, but likely other factors including lower quality and less health care."

Published in The Lancet, the research was presented at the European Society of Cardiology Congress.

It comes from the Prospective Urban Rural Epidemiology (PURE) study led by the Population Health Research Institute (PHRI) of McMaster University and Hamilton Health Sciences in Hamilton, Canada.

The high-income countries in the study were Canada, Saudi Arabia, Sweden and United Arab Emirates.

The middle-income countries were Argentina, Brazil, Chile, China, Columbia, Iran, Malaysia, Palestine, Philippines, Poland, Turkey and South Africa.

And the lower-income countries were Bangladesh, India, Pakistan, Tanzania and Zimbabwe.

The data comes from a large prospective international study documenting the frequency of common diseases in high, middle and low-income countries.

For this paper, the research involved 162,534 adults aged 35 to 70 from 21 countries who were followed for a median of 9.5 years.

Prof Yusuf added that the results are likely to be applicable to other countries with similar economic and social characteristics and health care.

Researchers also found that with higher country income, a higher proportion of deaths and hospitalisations were from non-communicable diseases compared to infectious diseases.

They also report the higher cardiovascular disease rates in poorer countries occurred despite much lower cardiovascular disease risk factors in poor countries.

Darryl Leong, the co-lead author of the study, and assistant professor of medicine at McMaster University, said: "The implications are that in HIC, while continued efforts to prevent and treat cardiovascular disease should continue, new efforts to reduce cancer are required."