MIAMI (AFP) - Chronic infections, smoking and pollution have contributed to skyrocketing cases of cancer in China, with an estimated 4.3 million new diagnoses last year and 2.8 million deaths, researchers said on Tuesday (Jan 26).

Lung cancer is the leading cause of cancer death in China, said the report published in CA: A Cancer Journal for Clinicians and led by Wanqing Chen of the National Cancer Centre in Beijing.

The report described cancer as a major public health problem in China, where the population is about 1.37 billion.

In the past, the burden of cancer has been difficult to estimate because research was based on small samples of the population - less than 2 per cent - and used old data sets from the 1990s, said the findings.

But higher quality data in recent years has come from a number of population-based registries via the National Central Cancer Registry of China.

The latest report is based on data from 72 local cancer registries, dating from 2009 to 2011 and representing 6.5 per cent of the population.

Using that information, researchers projected there would have been 4,292,000 newly diagnosed invasive cancer cases in 2015 in China.

That would equal almost 12,000 new cancer diagnoses each day, and 7,500 deaths.

The most common forms of cancer in men were lung, stomach, esophagus, liver, and colorectum.

In women, breast cancer was the most common, making up about 15 per cent of all new cases of cancer in Chinese women.

Following breast cancer, cancers of the lungs, stomach, colorectum and esophagus made up the bulk of women's cases.

Cancer is more deadly for men than women in China, killing men at a rate of 166 per 100,000 cases, about twice the rate for women.

Mortality rates from cancer since 2006 are down significantly for both males and females - about 21 per cent a year.

But due to the ageing and expanding population, the overall number of cancer deaths has substantially increased - by 74 per cent - during the same period, said the report.

Chronic infections of the stomach, liver and cervix led to nearly one third of all cancer deaths.

Tobacco smoking accounted for about one-quarter of all cancer deaths.

"Outdoor air pollution, considered to be among the worst in the world, indoor air pollution through heating and cooking using coal and other biomass fuels, and the contamination of soil and drinking water mean that the Chinese population is exposed to many environmental carcinogens," said the report.