Ask Our Doctor: Is Lung Cancer Curable and Can I Survive It?

Lung cancer can be curable when it is found early. The challenge is that early lung cancer often causes no symptoms, so many people are diagnosed only after it has spread.

Dr Steve Yang, respiratory physician at Mount Elizabeth Hospitals, explains what survival really means after a lung cancer diagnosis, why the stage of the cancer matters, and who should consider screening.

Is lung cancer curable?

Lung cancer can potentially be cured when it is found at an early stage. The stage of diagnosis is one of the biggest factors in what treatment is possible and how a patient does.

“A stage 1 cancer is a single small problem that can often be removed, which may cure it,” says Dr Yang. “By stage 4, however, the cancer has spread to other parts of the body.”

Detecting lung cancer early does not always guarantee a cure. Equally, stage 4 is not zero. A small number of patients with stage 4 lung cancer have lived for years with treatment and through clinical trials.

That said, Dr Yang cautions against waiting and hoping to be one of the exceptions.

What does it mean to survive lung cancer?

Survival is not only about staying alive.

Dr Yang explains: “Surviving with cancer is not the same as living. A person could be alive but bedbound, in a wheelchair, unable to work and dependent on others for feeding. That is surviving, but it is not living. This is why quality of life matters alongside length of life.”

The overall picture is improving. According to the Singapore Cancer Registry Annual Report 2023, cancer is being diagnosed more often, but age-adjusted cancer death rates have fallen, and more people are living at least five years after diagnosis.

For lung cancer, five-year relative survival in 2019–2023 was 24.2% in men and 40.7% in women, compared with 2.9% in men in 1973–1977.

Lung cancer still has one of the lowest survival rates of the 10 most common cancers in Singapore, second only to pancreatic cancer. This is why finding it early matters so much.

How common is lung cancer in Singapore?

Lung cancer is the third most common cancer in both men and women in Singapore, according to the Singapore Cancer Registry Annual Report 2023. Overall, about 1 in 4 Singapore residents may develop some form of cancer by the age of 75.

Dr Yang notes that lung cancer patterns differ by ethnic group.

Among Chinese and Indian men, lung cancer is the third most common cancer, while among Malay men it is the most common. Lung cancer makes up a smaller share of cancers in Indian women than in Chinese women. It is not yet clear whether environmental factors, genetic factors or both explain these differences.

What are the stages of lung cancer, and why do they matter?

Staging describes where the cancer is and how far it has spread. Dr Yang explains that it matters for three reasons:

• It guides treatment. A stage 1 cancer is not treated like a stage 4 cancer. Offering surgery for a stage 4 cancer, for example, would be the wrong treatment.
• It indicates the likely outlook. Doctors use survival data from around the world for each stage.
• It shows whether treatment is working. Staging is not a one-off. It is reassessed throughout treatment.

The stages can be understood like an outbreak spreading:

• Stage 0: abnormal cells that have not become cancer yet, but could.
• Stage 1: a single small tumour that can often be removed, which may cure the problem.
• Stage 2: the problem is bigger, and treating a single spot is no longer enough.
• Stage 3: the cancer has spread within the same organ or nearby areas.
• Stage 4: the cancer has spread to other parts of the body.

The time it takes to move from one stage to the next varies. Progression from stage 1 to stage 4 can take years, but in some patients it takes only a few months, depending on how aggressive the tumour is.

In Singapore, more cancers are now being found at stage 1, a sign that more people are going for screening and tests. However, the proportion diagnosed at stage 4 has stayed persistently high for almost 20 years, in both men and women.

Why is lung cancer often found late?

Many people expect pain or a cough to warn them of lung cancer. But early lung cancer often causes neither.

No pain. The pain nerve fibres are in the chest wall, not within the lung itself. A tumour growing inside the lung may not cause pain until it reaches the chest wall, by which time it is usually quite large.

No cough. The cough nerve fibres are in the air passages, such as the windpipe (trachea) and the bronchi, and not in the lung tissue. A cough usually develops only when the tumour involves an air passage, and by then the tumour may already be large. Coughs also have many other causes, including asthma, COVID-19, influenza and pneumonia, so a cough is easy to dismiss.

Lung cancer can therefore develop without pain or a cough. Learn more about lung cancer symptoms and causes.

Is a chest X-ray enough to screen for lung cancer?

No. Many people have a yearly chest X-ray as part of health screening and are reassured when it looks normal. However, a chest X-ray is not an effective way to screen for lung cancer.

An X-ray does not show the entire lung. Parts of the lung lie behind the heart, the ribs, the collarbone and other bones. A tumour hiding behind these structures, including near the pulmonary artery, may not be seen until it is much larger, by which time it could be stage 2 or stage 3.

A large US trial published in 2011 compared people who were offered yearly chest X-rays with people who were not, and followed them for 13 years. The number of deaths from lung cancer was about the same in both groups.

What is a low-dose CT scan, and what is it like?

A low-dose CT (computed tomography) scan is the test used to screen for lung cancer. You lie on a bed that moves in and out of the scanner, and you hold your breath briefly. The scan itself takes about five minutes. Including registration and waiting, the visit takes around 30 minutes, and results can often be ready quickly.

It is painless. There is no injection, no intravenous line and no need to fast, so you can have lunch and go for a scan.

The radiation dose is much lower than that of the CT scans used in the past. Dr Yang estimates that older scans were equivalent to about 70 chest X-rays, while a low-dose CT scan is equivalent to about 8 to 10.

In the 2011 National Lung Screening Trial, annual low-dose CT scans found lung cancers earlier and reduced deaths from lung cancer by about 20% compared with chest X-rays among people at high risk.

Why doesn’t everyone get a low-dose CT scan?

If low-dose CT can reduce deaths, why not scan everyone? Dr Yang explains that screening has trade-offs:

• Cost. A CT scan costs several times more than an X-ray.
• Radiation. The dose is low, but it is still radiation, and it adds up with repeated scans. Unnecessary scans are not helpful, while important scans are.
• False alarms. A scan picks up everything, whether it is cancer or not. Dr Yang likens it to fishing with a very fine net: you catch the fish, but you also catch the boot and the straw. A scan can show scar tissue, a lymph node or the after-effects of a bad infection. Until doctors can say it is nothing, the finding can cause stress and anxiety, and some people undergo a biopsy or scope that turns out negative.

Dr Yang walks through what happens when 1,000 people are screened: Most scans show nothing. That is reassuring, but a clear scan now does not mean a clear scan next year, because cancer can still develop later. A smaller group has a finding that doctors may simply monitor. A few need a biopsy or scope. And a very small group, about 3 in every 1,000, have a cancer found by screening that leads to a death being prevented.

That may sound like a small number, but for those people the difference is life-changing. Someone diagnosed early in their 30s or 40s can go on to work for another 30 to 40 years and be there for their children and grandchildren. Saving one life benefits the whole family. This is why guidelines exist: they weigh the benefits, costs and risks to decide who should be scanned, how, and when.

Who should go for lung cancer screening?

Singapore’s January 2025 lung cancer screening guidelines, as outlined by the National Cancer Centre Singapore, recommend an annual low-dose CT scan for people who:

• are aged 50 to 80 years,
• have a smoking history of at least 20 pack-years, and
• currently smoke or quit within the last 15 years.

A pack-year is one pack of cigarettes a day for a year, so 20 pack-years means a pack a day for 20 years. Occasional weekend smoking would not meet this threshold. Your risk of lung cancer falls with each year you stay smoke-free, which is why people who quit within the last 15 years are still included.

Screening is done once a year. A scan every three months is not necessary unless something has been found.

Screening may not be recommended for people who quit more than 15 years ago, or who have a serious medical condition, such as heart failure, that would make them unfit for treatment. If cancer were found, nothing could be done about it, so these patients are spared an unnecessary test.

What about non-smokers? Current guidelines do not recommend screening for non-smokers. Dr Yang stresses that guidelines are meant for the general population. They are not rules or laws, and lung cancer can develop in people who have never smoked. Read how one patient’s lung screening led to a stage 1 diagnosis.

His advice is not to assume that you will never get lung cancer, but not to be paranoid either. If you fall into a recommended group, go for a scan, so that a possible lung cancer can be treated early rather than late.

Can artificial intelligence help detect lung cancer earlier?

Dr Yang points to artificial intelligence (AI) as a promising area. Researchers are training AI to read X-rays and CT scans. AI tools can also consider factors such as smoking history, medical history and blood test results to estimate whether a person’s risk of lung cancer is high or low, which can help decide who should go for screening.

When AI is combined with CT scans, more cancers can be picked up. AI can also flag findings that are not important, but it can be trained, using thousands of scans, to tell apart findings that are likely benign from those that are likely cancer.