Iconic Community / 19 Nov, 2021

Why do non-smokers also get non-small cell lung cancer?

Dr Hsieh Wen-Son

Understanding the causes of lung cancer

There are two main types of lung cancer: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). The latter accounts for 10% to 15% of all cases of lung cancer.

I have never smoked in my life, why did I get lung cancer?

No symptoms in the early stages of lung cancer

Cigarette smoking is the number one risk factor for SCLC and NSCLC. However, the incidence of NSCLC among non-smokers has increased significantly. There has been increased incidences of people in their 30s and 40s who have never smoked before getting NSCLC. Nonetheless, NSCLC usually has better outcomes compared to SCLC.

The cure rate of Stage I NSCLC with surgery alone is 70% to 80%, and the cure rate of Stage I SCLC after surgery with concurrent chemotherapy and radiation therapy is estimated to be around 25% to 30%.

Besides smoking, the other causes of NSCLC are relatively unknown. However, there is evidence showing environmental factors such as pollution and exposure to carcinogens can increase risk.

Since lung cancer does not present any major signs and symptoms in its early stages, it can be difficult to detect. Symptoms often do not appear until the disease is already at an advanced stage. Symptoms of lung cancer can include a persistent cough, chest pain and shortness of breath.

It is important to understand that being diagnosed with lung cancer is not a ‘death sentence’ as many people have this misconception.

New and advanced drugs have fewer side effects

There are many different types of effective treatments for the two types of lung cancer above.

Usually, chemotherapy and radiation therapy are offered as treatments for SCLC. Although the response to these treatment methods is good, SCLC can return within three months. NSCLC also responds to these proven treatments but tends to relapse at a slower rate.

Patients can have a better quality of life due to advancements in chemotherapy drugs which are more effective with fewer side effects. Supportive therapy is also effective in helping patients manage common side effects of chemotherapy, such as nausea and vomiting.

Targeted therapy can also be used for the treatment of patients with NSCLC whose tumours have gene mutations that can lead to cancer growth and spread. The most common therapies include oral drugs, which are highly effective and generally do not cause many side effects in patients with these types of gene mutation cancer cells.

As most of the oral drugs were developed to specifically target cancer cells, it is highly effective in controlling cancer and generally do not cause much side effects in patients with gene mutation cancer cells.

Advancements in targeted therapy

Another targeted therapy that has made significant progress in the past decade is immunotherapy – a therapy which stimulates the immune system to attack tumours.

Patients generally receive drugs that stimulate T cells (a type of white blood cell) in the immune system to attack the tumour or drugs that block a protein called PD-L1.

According to the National Cancer Institute of the United States, PD-L1 naturally exists in the human body and acts as a ‘brake’ to prevent immune cells from attacking harmless and healthy cells in the body.

Immunotherapy improves survival rate

Immunotherapy drugs can ‘unmask’ cancer cells, block protein cells on the surface of the tumour cells and ‘reactivate’ the body’s own immune system to better identify cancer cells and attack them directly.

A study presented at the European Society for Medical Oncology Virtual Congress 2020, showed that about 30% of patients whose lung cancer expressed high levels of PDL1 who have undergone immunotherapy have a five-year survival rate – something that was unheard of five to six years ago. In addition, 10% of patients had complete disappearance of their cancer.

In summary, treatment for lung cancer has vastly improved. There are more options, which can help lung cancer patients to control their condition better, increase survival rates, and improve their, as well as their carers’ quality of life.

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