In the shadow of one of China's top cancer hospitals in Beijing, a catacomb-like network of ramshackle brick buildings has become a home-from-home for hundreds of cancer patients and their families waiting for treatment.

The cluster of nine buildings, connected by dark, narrow passageways, offers cheap accommodation for patients unable to afford a coveted hospital room, a reflection of the vast inequalities in China's overburdened health care system.

These "cancer hotels" have sprung up near hospitals around the country to house some of the more than three million people diagnosed with cancer in China every year.

Patients often travel hundreds of miles to city hospitals because of poor facilities in their home regions, creating a wave of cancer "refugees" often living on a shoe-string as they struggle to pay for care.

"There's an imbalance between the big cities and small ones. Good doctors don't want to work in small places," said Liu, 46, a migrant worker who brought his wife more than 750 km (450 miles) to see a specialist in the capital in May.

His wife, Wang, 42, was diagnosed with cervical cancer at the beginning of the year, and was told by family she should leave her hometown in Inner Mongolia for treatment.

"If you have some serious illness then you'd better go to Beijing," said Liu. Both husband and wife asked that Reuters use only their surnames to protect their privacy.

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A manager of one of the hotels said most patients stayed for between several months and a year while they waited for treatment.

FINANCIAL BURDEN

The costs all add up. A cheap train ticket for Wang and Liu's 16-hour journey was 321 yuan ($48), while a room at the hotel sets them back about 70 yuan a night, half the price of a hospital bed.

Their simple room, with a translucent blue shawl hanging across the door, had a television and fan. They can also cook at the hotel.

The financial burden for Chinese patients with serious conditions like cancer or diabetes can be overwhelming. Official data shows that up to 44 percent of families pushed into poverty were impoverished by illness.

Stories abound of patients or their relatives going to extremes to pay for care: turning to unapproved treatments, sleeping rough or even donning fancy dress in public to raise funds.

State health insurance does reach nearly all of China's 1.4 billion people, but coverage is basic, meaning patients, on average, foot almost half the bill. That can rise much higher for chronic or complex diseases like cancer.

"The hardest part for us is the money," said Pan, 60, who came to the Beijing cancer hotel with his wife, Huang, after she was diagnosed with rectal cancer in 2013. "We are farmers, we have already spent over 270,000 yuan ($40,500) since 2013."

Many people turn to friends, relatives or shadowy lenders to pay for travel and treatment. Many end up in queues outside hospitals paying ticket touts or doctors to speed things up.

"Only half our costs can be covered by the medical insurance," said Pan.

"We're not city folk who can lend out thousands of yuan at a time. Families in our area are poor. We have to borrow money for treatment."