The prognosis of lung cancer patients remains the worst of all, with an average survival time of only six to nine months.
The World Health Organisation has declared cancer the second-biggest cause of death in the world.
In 2012, it recorded 14 million new cancer cases. The number is expected to keep growing in the next two decades, with an estimated 70 per cent increase.
Among the various types of cancer, lung cancer contributes considerably to the statistics of major deadly diseases affecting both males and females all over the globe.
"The fact is that 50 per cent of the median survival time of lung cancer patients is only between six and nine months. Only 40 per cent of those at an advanced stage survive for one year," explained Sita Andarini, a pulmonologist at Persahabatan General Hospital in Jakarta at a discussion.
The referral hospital for respiratory diseases also recorded that during 2000-2009, new lung cancer cases increased fivefold, from about 273 cases in 2000 to 938 in 2009.
"Last year, new lung cancer patients reached 1,355," she said.
As for the worst prognosis of lung cancer patients, Sita attributed it to the difficulty in detecting this particular disease, which resulted in most patients seeking medical treatment only after the cancer had reached an advanced stage.
Early symptoms, such as chronic cough and gasping, are often dismissed as an ordinary cough rather than a serious condition. When coughing produces blood accompanied by hoarseness or sudden non-asthmatic wheezing, treatment is often then sought, only to discover that it is an advanced stage of lung cancer.
At the advanced stage, there's a limited choice of treatment to preserve the quality of life of a lung cancer patient and prolong their life, which explains the low mortality rate of lung cancer patients.
Nonetheless, lung cancer patients can now pin their hopes on immunotherapy, which can be applied in the course of treatment.
Regarding how this therapy works in killing lung cancer cells, Sita pointed to the human body's natural defence mechanism to eliminate cancer cells. But under certain conditions, human immune cells are rendered inactive by cancer cells' substances that weaken immune response or create immune tolerance.
"Cancer cells are very smart and possess an antigenic switching mechanism. When our immune cells identify cancer cells' antigens as foreign bodies that must be destroyed, they instruct lymph glands to produce immune cells to bombard cancer cells. But before they are attacked, the antigens change so that they aren't recognised as enemies by the immune cells, allowing cancer cells to spread," said Sita, who has researched immunotherapy for 15 years.
Immunotherapy, she said, serves to strengthen the response of immune cells so as not to be fooled by cancer cells.
She explained that immunotherapy by means of immune checkpoint inhibitors is the treatment of cancer by preventing any interaction between the immune system's T cells and cancer cells.
When cancer cells and T cells interact, she said the former would produce a protein called Programmed Death-Ligand 1 (PD-L1) to paralyse T cells so that immune cells don't recognise and kill cancer cells.
"The immunotherapy drug will inhibit such interaction to enable T cells to identify and destroy cancer cells," she said.
In Indonesia, the anti-PD-L1 immunotherapy drug, Pembrolizumab, has been approved by the Food and Drug Monitoring Agency (BPOM) for the treatment of lung cancer at an advanced stage after the failure of first-line therapy.
Phoebe Kusuma, medical affairs manager for Oncology MSD Indonesia, said early research on this drug had been conducted for melanoma, or skin cancer. But in its development the immunotherapy drug responded well to lung cancer.
"In Europe and America this medicine is approved not only for melanoma and lung cancer but also for head and throat cancer. We're also studying its use for 30 other cancers," he added.