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More aggressive, spreads quickly: Why small cell lung cancers are hard to beat

A new first-line treatment option has been approved for people battling extensive-stage small cell lung cancer, an aggressive disease strongly associated with smoking.

More aggressive, spreads quickly: Why small cell lung cancers are hard to beat

Cigarette smokers are at a much higher risk of developing small cell lung cancer, a fast-spreading cancer. Photo: Shutterstock

There is a reason cigarette packs clearly call out “Smoking is injurious to health”. Whenever you light up a cigarette, consider these hard truths: Every puff you take, cancer-causing substances wreak havoc on the cells that line the lungs. Over time, this repeated assault can lead to irreparable damage and put you at risk of diseases such as lung cancer.

Research has shown that cigarette smoking is a top risk factor of lung cancer, which has consistently been one of the most frequently occurring cancers in Singapore in the last 50 years. It is also the most lethal cancer here and around the world.

From 2013 to 2017, lung cancer accounted for over 6,000 deaths – more than 3 per day – in Singapore, according to Singapore Cancer Registry data. Smokers have a 15 to 25-time higher risk than non-smokers, but non-smokers are not spared either.


Cigarette smoking is strongly associated with two major types of lung cancer: Small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Small cell lung cancer is usually the more aggressive of the two, whereby the tumour grows quickly and spreads early to other parts of the body.

Accounting for 10 to 15 per cent of all lung cancer cases, a diagnosis of SCLC can be fatal for patients. Further complicating matters are the lack of early signs and low awareness of SCLC. Dr Lim Hong Liang, senior consultant of Medical Oncology at Parkway Cancer Centre, said: “The early stages of the disease are often missed because it is asymptomatic until after the tumour has grown to a large size and has started to spread to nearby lymph nodes or metastasise to other parts of the body.”

At the time of diagnosis, the majority of patients would have extensive-stage SCLC. The cancer is said to be extensive when it has spread to other areas including the other lung, to the lymph nodes on the other side of the chest or to distant organs.

Depending on factors including the stage of the disease, Dr Lim said the general five-year survival rate for people with SCLC is 6 per cent. Individuals at Stage 1 have a survival rate of 31 per cent and those who have reached Stage 4 or extensive-stage SCLC have a survival rate of 2 per cent.


As World No-Tobacco Day draws close, Dr Lim shares that people who smoke are at the highest risk for SCLC. One may also be at higher risk for lung cancer if they are frequently exposed to second-hand smoke.

Dr Lim shared that when the tumour starts to spread, patients may experience symptoms like persistent coughing or hoarseness, coughing up blood, shortness of breath, wheezing, chest pain or discomfort, loss of appetite and fatigue.

However, even these red flags may be missed. “These symptoms can occur with other pre-existing conditions that the patient has, which further delays diagnosis,” Dr Lim added.

Smokers may not realise that their nagging cough may be a sign of something more dangerous. Photo: Shutterstock

For example, a heavy smoker may mistake a persistent cough due to cancer for a smoker’s cough. The latter is a nagging cough that may occur in long-term smokers due to irritants in cigarette smoke.


Existing conventional treatment options for extensive-stage SCLC are limited.

Dr Lim said: “The treatment options are based mainly on the extent of the cancer, but other factors like the patient’s overall health and lung function are also important considerations. Sometimes, more than one type of treatment is used.”

In majority of the cases, chemotherapy is used as first-line treatment. In patients whose tumour is still confined to the lung, radiation to the lung and adjacent lymph nodes is added to chemotherapy, Dr Lim added.

Dr Lim said surgery is rarely used in SCLC although it may be considered in very rare cases where the tumour is small and has not spread to other areas.

“As the majority of SCLC are incurable, aggressive supportive and palliative treatment remains an important component in the overall management of SCLC,” he said.


For the first time in more than two decades, a new treatment option presents renewed hope for patients living with extensive-stage SCLC.

Immunotherapy in combination with chemotherapy has been approved by the Health Sciences Authority in Singapore as a first-line treatment for extensive-stage SCLC patients.

Immunotherapy is a cancer treatment that harnesses the patient’s own immune system to fight cancer cells. As a first-line treatment, the new combination treatment can be used as an option before other treatment methods.

Dr Lim said: “I had a patient on this treatment and he had his disease well under control for almost a year, with the side effects being manageable, and I am optimistic of the same health outcomes for other patients.”

Studies have shown statistically significant improvements in the overall survival rate with the addition of immunotherapy to chemotherapy when compared to chemotherapy alone. Safety and tolerance of the new combination treatment also appeared similar to that of chemotherapy alone.

Dr Sivabalan Sivanesan, medical director of Roche Singapore, said: “As the new first-line treatment in over 20 years, this treatment option enables Roche to redefine the standard of care for treating extensive-stage SCLC. We are excited to renew a sense of hope for patients living with extensive-stage SCLC and look forward to advancing survival rates and overall health outcomes.”


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