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Lung cancer: What you need to know

Lung cancer is the leading cause of cancer deaths in Singapore. Dr Chin Tan Min from Parkway Cancer Centre answers some questions.

I have never smoked in my life. Can I still get lung cancer?

Smoking is the top risk factor for lung cancer. Smokers are 15 to 30 times more likely to get lung cancer than non-smokers.  The earlier in life a person starts to smoke and the more years he has smoked, the greater the risk of lung cancer. Smokers who stop smoking have a reduced chance of developing lung cancer, and the longer one has stopped smoking, the lower the chance.

However, it is important to remember that even if you don’t smoke, you still can get lung cancer. Other risk factors include breathing secondhand smoke, exposure to certain chemicals such as asbestos and other carcinogens, as well as a family history of lung cancer.

Are there different types of lung cancers?

There are two general types – small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC).

SCLC is less common than NSCLC, occurring in about 15 per cent of lung cancer patients. Almost all patients who have small cell lung cancer are smokers. It is a more aggressive form of lung cancer and can spread quickly to other parts of the body. The survival rates for the more advanced stages of the disease are lower compared to those with limited stage disease.

Non-small cell lung cancer is more common, accounting for 85 per cent of all lung cancers. Depending on the stage of the cancer, treatment may include surgery, radiotherapy, or more systemic forms of treatment such as chemotherapy, and more recently, targeted treatment and immunotherapy.

Are women less likely to get lung cancer than men?

Because more men smoke than women, lung cancer is more common among men. But it is still the third most common cancer among women in Singapore, and about eight in 10 women who have lung cancer are non-smokers or former smokers.

If I cough a lot, does that mean I may have lung cancer?

Chronic coughs may not necessarily be a precursor to lung cancer. However, if you are coughing a lot, you should get it evaluated. If you have been coughing constantly for over a month, you should see a doctor and get it checked out.

Many lung cancers are, unfortunately, diagnosed when the disease is in an advanced stage. Typical symptoms, other than coughing, are coughing out blood, shortness of breath, fatigue, lack of appetite, unexplained weight loss and chest pains.

Are there regular screenings we can do to check for lung cancer?

At this point, there are no tumour marker tests specific for lung cancer.

As for chest X-rays, it’s not proven to be effective in cutting down on the mortality rate of lung cancer. And we must remember that one X-ray exposes a person to about one day of natural background radiation that any person is exposed to as part of his or her daily life, approximately at 0.01 millisievert (mSv).

CT scans can also be done, but the radiation exposure from one CT scan is much more than that of a chest X-ray, usually quoted at 4 to 7 mSv, averaging similar to the average background radiation exposure a person gets in a year. Low-dose CT scans have less radiation exposure.

We typically do not recommend annual CT scans unless the person is at high risk (heavy smokers or family history of lung cancer) of getting lung cancer. This is because we have to balance the benefits of early detection against the radiation risks from doing too many scans.

What are the typical treatments for lung cancers?

For Stage 1 and 2 lung cancers, we usually recommend surgery to completely eradicate localised tumour cells. Surgery is the best chance of cure. In some cases, we follow up with adjuvant chemotherapy to totally clear cancer cells to reduce chances of the cancer coming back.

For more advanced stages, we may use a combination of radiation therapy and/or chemotherapy. Nowadays, we also use targeted treatment and immunotherapy.

Previously, when we used chemo-therapy mainly for Stage 4 lung cancers, the median survival rate was just six to eight months.

In 2004, we started using targeted therapy and in 2015, immunotherapy. These have improved survival rates quite significantly, and the average Stage 4 lung cancer patient lives  for two to three years.

Are these new forms of treatment successful?

Targeted therapy uses drugs to stop the growth and spread of cancer cells.

For example, lung cancer cells sometimes have a mutation in the epidermal growth factor receptor (EGFR) gene, which is responsible for causing cancer cells to grow and divide quickly. Drugs called EGFR inhibitors can help to block these signals and stop cancer growth. There are also anaplastic lymphoma kinase (ALK) inhibitors that work in the same way.

Patients who take ALK inhibitors can live for two to three years without any recurrence of the cancer.

Immunotherapy is the enhancement of one’s own body’s immune system to kill cancer cells.

Cancer cells have the ability to “camouflage” themselves such that they go undetected by our immune system. Immunotherapy unveils these tumour cells so that our immune system can fight them.

Studies have found that immunotherapy has significantly improved survival rates in lung cancer patients. The biggest excitement for immunotherapy in Stage 4 lung cancer patients is the “tail-end” of patients who achieve long-term good control of disease after treatment with immunotherapy.

TYPES

85% of lung cancer patients have non-small cell lung cancer (NSCLC). Less aggressive than SCLC, and if discovered early, treatment may offer a chance of cure.

15% of lung cancer patients have small cell lung cancer (SCLC). Almost all of them are smokers. This aggressive form of lung cancer can spread quickly to other parts of the body.

RISK FACTORS

#1 Smoking
Smokers are 15-30x more likely to get lung cancer than non-smokers. Other factors include secondhand smoke, exposure to chemicals and carcinogens, and family history of lung cancer.

TRENDS

No.1 Lung cancer is the leading cause of cancer deaths in Singapore.

No.2 most common cancer among men in Singapore.

No.3 most common cancer among women in Singapore.

Written by Ben Tan