Lung cancer is the third most common cancer for both men and women, according to the Singapore Cancer Registry Annual Report 2019. Not only does the disease reflect a higher incidence of it in men at 13.7 per cent compared to women at 7.7 per cent, it is also the top leading cause of death in men and the third for women. 

For Lung Cancer Awareness Month in November, Dr Amit Jain, a senior consultant in the Division of Medical Oncology at the National Cancer Centre Singapore (NCCS), shares what you need to know about the disease and the treatments available so that patients can make informed decisions.
Q: What are the risk factors for lung cancer? 

Smoking remains the most important modifiable risk factor in getting lung cancer. But in societies like Singapore where smoking rates are lower than in some European countries, it is clear that a substantial proportion of lung cancers occurs in people who have never smoked. 

There isemerging evidence that small pollutant particles may be driving some cancer mutations that eventually lead to lung cancer. This was shown to be the case in experiments involving mice and is now an area of active research to unravel causality in humans too.

While there are occasionally some cases that seem to run in the family, lung cancer is not generally attributable to a single genetic cause but may be related to environmental factors. 

Q: How is the treatment of lung cancer dependent on the type and stage of the disease?

There are two main types of lung cancer: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). It is important to note that treatments are recommended based on the needs of individual patients. 

For SCLC, a limited stage of the disease is usually treated with chemotherapy and radiotherapy, while more advanced stages may be treated with chemotherapy and immunotherapy. Some patients may also be treated with radiotherapy, depending on the site of their cancer, its spread and the response to treatment. 

Treatment varies for NSCLC, depending on the cancer stage. In early stages, surgery will be proposed to remove part of the affected lung. This may be followed by chemotherapy, immunotherapy and targeted therapy, depending on the extent of the spread and the subtype of the cancer. 

For cancers at a more advanced stage, a combination of treatments may be proposed, comprising surgery, radiation, chemotherapy, targeted small molecule inhibitors and immunotherapy. The plan for patients is discussed at multidisciplinary tumour boards before treatment is started.

Q: How are new therapies raising the bar in the treatment of lung cancer? 

When the mutation that promotes cancer growth has been identified, patients may benefit from certain drugs to control their cancers. Known as targeted therapies, such drugs generally suppress cancer cell growth by targeting specific abnormal proteins in the cancer. In some instances, this could also lead to regression of the cancer. 

The immune system can also be harnessed to kill cancer cells. Immune checkpoint inhibitors, which help take off the brakes that cancer may put on immune cells, have been seen to be successful in treating lung cancer. 

Patients with cancer cells that have a higher level of PD-L1, a kind of protein, may have a higher chance of response to some immune checkpoint inhibitors.

Q: What are some of the myths about lung cancer? 

Myth 1:“Never-smokers” can’t get lung cancer. 
Unfortunately, they can. In Singapore, a 2006 study by NCCS found that 32 per cent of NSCLC patients were never-smokers and another study done by NCCS in 2018 showed this number increased to 48 per cent. While it is challenging to identify who is at high risk among people who have never smoked, this is currently an area of active research to find the best way to do so. However, it is worth noting that smoking is carcinogenic.

Myth 2: Patients with lung cancer shouldn’t exercise. 
Some patients think they’ll get breathless if they exercise, and that they should rest more. But we recommend that patients exercise daily to stay fit. This can help them feel better when their condition improves, so that they can enjoy a better quality of life. 

Exercises should mimic daily activities. For example, a patient who struggles to stand after sitting could try repetitions of it. Fitter patients may want to try climbing stairs and build up capacity over time. Lung cancer patients are welcome to join our exercise interest group (#lungcancerwillnotkeepmedown); e-mail for details.

Myth 3: You have to become vegetarian or avoid certain foods to starve the cancer. 
It is likely that patients will need to eat more to avoid loss of nutrients. I recommend that patients are free to eat anything and be happy, although it is important to have nutritious, balanced meals, and get enough protein to maintain and grow muscles. Consult a dietician if in doubt. 

Q: How can lung cancer patients manage their condition better and improve their quality of life? 

Having a frank, open discussion with loved ones and your attending doctor may help set a realistic tone for what the cancer journey may entail. These discussions are best carried out early on, and should be as candid and kind as possible to help you cope and plan better. Eat well, exercise and understand what’s coming next, so you can live life to the fullest.

Q: What more can be done in the fight against lung cancer? 

The majority of lung cancer cases are diagnosed at stage 4, which is incurable. Early detection offers a chance of better outcomes, although rates of cure may still be modest and relapse is possible. Screening for high-risk populations, such as smokers, is recommended. 

Next year, NCCS will begin a large clinical study called Singapore Lung Cancer Screening Through Integrating CT With Other Biomarkers (SOLSTICE) to assess the impact of screening in both smokers and “never-smokers” with relevant risk factors.

Dr Amit Jain 
Senior Consultant 
Division of Medical Oncology 
National Cancer Centre Singapore