1. Lung cancer in never smokers (LCNS) Sun S., Schiller J.H. & Gazdar A.F. Nat Rev Cancer, October 2007: 7: 778-790
2. www.lungcancercoalition.org/en/pages/facts
3. Parkin DM, Bray F, Ferlay J and Pisani P. CA Cancer J Clin 2005; 55: 74-108.


What is lung cancer?

Lung cancer is a malignant tumour that grows in one or both lungs. Lung cancer usually develops from cells that line the airways and nearby glands. This is probably because these cells are the ones that come in contact with the air we breathe which may contain carcinogens (agents that cause cancer).

In lung cancer, the change from normal cells into cancerous cells probably happens over a period of years.

Worldwide around 1.3 million people are diagnosed with lung cancer each year. Lung cancer is the most common cancer diagnosed in men and the fourth most common cancer diagnosed in women.

What causes lung cancer?

There are several factors that are known to contribute to the development of lung cancer. Smoking is the number one cause of lung cancer. However while smoking is an important risk factor in developing lung cancer, there are many people with lung cancer who have never smoked. Other factors that predispose to the development of lung cancer include the following:

  • Exposure to chemicals in the air - such as asbestos and radon
  • Lung diseases - that can block airflow to the lungs such as chronic obstructive pulmonary disease (COPD) or tuberculosis
  • Genetics - people with a relative who had lung cancer are at higher risk for developing lung cancer
  • Age - lung cancer occurs more often in people over 65 years of age.

Cigarette smoke contains at least 43 different carcinogens. It has been associated with various cancers including lung, oesophagus, mouth, stomach, pancreas and liver.

Smoking accounts for at least 30% of all cancer-related deaths and 87% of lung cancer deaths. Approximately 50% of new lung cancers are diagnosed in former smokers. The risk of lung cancer increases with an increase in the total number of cigarettes smoked, referred to as pack-years (number of packs smoked per day times the number of years smoked).

Second-hand smoke also contains carcinogens. It is estimated that each year in the US between 5,000 and 10,000 people are diagnosed with lung cancer, which is thought to be associated with breathing second-hand smoke.

Quitting smoking decreases the risk of developing lung cancer. Ten years after quitting, the risk has decreased by half. Although smoking cessation lowers this risk of developing lung cancer, the risk never decreases to the level of people who have never smoked. Recent findings for smokers who have been diagnosed with lung cancer suggest that those who quit smoking during their lung cancer treatment may live longer than those who continue to smoke during treatment.

It’s never too late to quit smoking! If you currently smoke and would like to quit, talk to your doctor or pharmacist about the different options to help you stop smoking.

Lung Cancer – women get it too

It’s a long standing myth that only men get lung cancer. While there are no recent stats available in South Africa, AstraZeneca estimates that while approximately 1 in 69 South African males will suffer from the disease, women are most definitely also at risk. It’s approximately the 4th most prevalent cancer among South African females with 1 in 210 diagnosed with the disease. The truth is lung cancer is the biggest cancer killer among women worldwide so it’s time we got proactive. Don’t ignore persistent excessive coughing and chest pains – early detection increases treatment options and survival.

Types of Lung Cancer

There are several different types of lung cancer, but the majority of cases fall into two main categories:

  • Small-cell lung cancer (SCLC) – 20% of cases
  • Non-small-cell lung cancer (NSCLC) – 80% of cases

These two types of lung cancer behave differently and are treated differently. This section will focus on non-small-cell lung cancer (NSCLC) because it’s the most common form.

Briefly, small-cell lung cancer (SCLC) is less common and tends to be more aggressive. It is often more advanced at the time of diagnosis and treatment usually involves chemotherapy and radiation therapy.

Non-small-cell lung cancer is divided into different subtypes based on the type of cell that the tumour develops from. The main different types of NSCLC are:

  • Adenocarcinoma
  • Squamous cell carcinoma
  • Large cell carcinoma.
Adenocarcinoma is the most common subtype and accounts for 30%-35% of all NSCLC cases. These tumours usually develop at the edges of the lungs, but they can sometimes occur toward the centre of the chest. They are often slow growing and don’t typically cause symptoms in their early stages. As a result, adenocarcinomas are often diagnosed at an advanced stage. The number of cases of adenocarcinoma has increased over the past few decades. It is the most common sub-type of lung cancer in women and in non-smokers.

Squamous cell carcinoma accounts for about 30% of all NSCLC cases. Unlike adenocarcinomas, this type of cancer is strongly associated with smoking. These tumours are usually found in the larger airways and toward the centre of the chest.

Large cell carcinoma accounts for 10%-20% of all NSCLC cases. These tumours grow at the edges of the lungs and are more difficult to diagnose. They tend to be fast growing and spread to other areas of the body (metastases). Like squamous cell carcinomas, these tumours are associated with smoking.

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