Mr Cheong Weng Kee, 76, owner of a restaurant featured in the Michelin Guide, had a health scare three months ago when he was diagnosed with Stage 4 lung cancer.
A heavy smoker, he had been taking antibiotics to treat his breath- lessness. He often worked 12-hour days at the restaurant and smoked around 15 cigarettes daily to cope with the stress.
He was admitted to hospital when his condition worsened. Doctors drained more than one litre of fluid which had accumulated in one side of his chest cavity.
Dr Donald Poon, a medical oncologist at Raffles Cancer Centre who treated him, offered him an alterna- tive treatment - immunotherapy.
Immunotherapy was approved by the Health Sciences Authority in May as a first-line treatment for patients like Mr Cheong, who have certain types of non-small cell lung cancer in the advanced stages.
Non-small cell lung cancer is the most common lung cancer.
Mr Cheong decided to quit smoking and try immunotherapy. He recalled: "The nurse showed me the liquid drained from my chest cavity.
"It had a layer of oil and smelled of cigarette smoke, even though I had not smoked after being admitted to hospital. That was when I realised how serious it was."
He received the first infusion of the drug, pembrolizumab, more than a week later.
Conventional chemotherapy kills cancer cells but can also affect healthy cells, whereas immunotherapy enhances the body's natural defences against cancer.
Cancer cells can thrive in the body because the immune system does not recognise them as intruders. Immunotherapy can help the immune system find the cancer cells and destroy them.
Dr Poon said that, in some cases, patients who undergo immunotherapy suffered fewer side effects, had a longer interval between the time they started treatment and the time they suffered a relapse of the disease, and lived longer than those who had chemotherapy.
After five sessions of the treatment, Mr Cheong's cancer is now under control.
It costs between $12,000 and $15,000 without subsidies for 200mg of pembrolizumab, which is administered every three weeks.
In contrast, a chemotherapy session costs between $4,000 and $5,000. For Mr Cheong, the cost is mostly paid through Medisave and insurance.
He was back at work after the second session in June, but his wife and four children made sure he had only light duties at the restaurant.
Mr Cheong's Capital Restaurant in New Bridge Road was included in the Michelin Guide Singapore last year and this year.
Of the immunotherapy treatment, he said: "There were no side effects, I felt completely normal."
Dr Poon said Mr Cheong was fortunate as immunotherapy is not always well tolerated by the body.
"Immunotherapy can, on occasion, cause very serious complications if the immune system is over- stimulated and starts attacking the normal vital organs," he said.
"On rare occasions, this may result in organ failure and severe complications worse than chemotherapy."
The potential long-term adverse effects are still unknown since the treatment is relatively new, said Dr Poon. It became more widely used only about a year ago.
An ongoing research trial that started in 2014 in 16 countries, excluding Singapore, found that more than half of the 305 non- small cell lung cancer patients who went through immunotherapy had a period of more than 10 months without the disease becoming active, compared with six months for those who underwent chemotherapy.