Global cancer cases rise by a third in a decade as life expectancy and unhealthy habits increase, finds major study

'Lifestyle cancers' linked to smoking, bad diet and sun exposure rising particularly fast in developing countries

Patients on a chemotherapy ward in Ghana are among the million new cancer cases in sub-Saharan Africa, a number expected to double in a decade (Reuters)

The number of cancer cases diagnosed around the world each year has risen by almost a third in the past decade as increasing life expectancy means millions of more people will be diagnosed in their lifetime.

Researchers said there was also cause for concern in the rise in skin, lung and colorectal cancers, which could largely be prevented by addressing lifestyle habits like smoking and diet.

The Global Burden of Disease Cancer Collaboration audits diagnosis rates and deaths of 29 types of cancer around the world each year.

Its latest report, published in the JAMA Oncology journal, shows there were 17.2 million cancer cases, and 8.9 million cancer deaths around the world in 2016.

This is an increase of 28 per cent in new cancers between 2006 and 2016, much of which is attributed to an expanding and ageing population as well as screening and diagnostics which can catch cancers sooner.

However, the biggest growth has been seen in low and middle income countries – emerging markets which have been targeted by tobacco giants and an influx of cheap convenience foods in recent decades.

“This highlights the importance of focusing tobacco control efforts on lower socio-demographic index countries (SDI),” the authors wrote. “To avoid these countries’ having to experience the same tragedy of unnecessary tobacco related deaths that many high SDI countries have had to face.”

Lung cancer remains the world’s biggest cancer killer, accounting for 20 per cent of all deaths in 2016, although among women breast cancer remains the biggest killer.

The authors add that the growing recognition of air pollution from cars and industrial sources and even household chemicals must be considered as “important risk factors” for cutting lung cancer deaths.

The increasing popularity of alcohol alongside processed foods and sedentary lifestyles are also factors that have contributed to a rise in colorectal cancers above the level expected from population growth alone.

Australia and New Zealand have some of the highest rates of cancer diagnosis, the audit found.

“While the increase in lung, colorectal, and skin cancers over the past decade is concerning, the prevention potential is substantial,” said Dr Christina Fitzmaurice, assistant professor of global health at the University of Washington.

“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.”

The rise in lifestyle cancers has been offset in part by a drop in cervical and stomach cancers, which are caused by infectious diseases like the human papillomavirus.

However, this also shows the inequities that remain in cancer care. Women in less economically developed countries, where costly vaccination and screening programmes are less common, are four times more likely to develop cervical cancer and it is the biggest cancer killer in these regions.

“Ensuring universal access to health care is a vital prerequisite for early detection and cancer treatment,” said Dr Fitzmaurice. “Improving access to advanced diagnostic technologies not commonly available in low-SDI countries is a critical step towards achieving health equity globally.”

While wealthier nations with longer life expectancy and national screening programmes top the rankings for new diagnoses, it is developing countries where there are the most cancer deaths.