In China, cancer rates are exploding and for the first time the extent has been revealed.

Last year, more than four million people were diagnosed with the disease and nearly three million died from it, research from the American Cancer Journal of Clinicians showed.

In some of the industrial provinces, lung cancer rates have increased a staggering four-fold, but authorities seem reluctant to acknowledge — let alone deal with — the epidemic.

The Cancer Institute and Hospital in central Beijing is struggling to cope with ever-increasing caseloads.

Every day, hundreds pour in from all over China.

People can wait months for a doctor's appointment, but often it is too late for treatment and the cancer is too advanced.

Lung cancer 'from air pollution'

A man who wanted to remain unidentified said his wife had just been diagnosed with lung cancer and, like most we spoke to, he was sure of what caused it.

"The reason is the work environment and the air pollution, she had no cover," he said.

The couple come from the coal-producing province of Shanxi. The man said his wife was exposed to chronic air pollution when she worked on the regional railways.

"At night if you use a torch, you can see it best, the air is full of small particles, if you work indoors there's less chance of getting cancer," he said.

Cancer has been the leading cause of death in China since 2010, with lung cancer causing the most deaths.

With the increase in air pollution over the last decade, lung cancer has increased 50 per cent in Beijing.

But the most dramatic increases have been in the coal and steel producing provinces.

Pollution's health impacts censored by authorities

Figures just released from Tumor Hospital at Hebei show lung cancer rates increased 306 per cent from 1973 to 2012.

Researchers say extreme air pollution has contributed to the rise.

"There's already sufficient evidence that exposure to outdoor pollution will cause lung cancer and it's the reason why the international agencies on research on cancers and the World Health Organisation have already classified air pollution and PMP 2.5 particles as class one carcinogens," Dong Liansai from Greenpeace East Asia said.

Chinese authorities routinely censor news about health impacts and chronic pollution.

The Chinese cancer specialist and doctors the ABC approached for an interview refused to comment.

But the report published in the American Cancer Journal for Clinicians by Chinese academics this month said cancer rates were expected to rise.

It cited prolonged exposure to pollution, chronic infections and heavy smoking as risk factors.

In China, half of all men still smoke, consuming a third of the world's cigarettes.