Surprising causes of lung cancer

It is estimated that more than 14,500 people were diagnosed with lung cancer in 2022 in Australia. The average age at diagnosis is 71 years old. Lung cancer is the fifth most commonly diagnosed cancer in Australia, and it is estimated that one in 20 people will be diagnosed by the time they are 85.

Lung cancer occurs when abnormal cells grow uncontrollably in the lungs, generally starting in the lining of the bronchi or other lung tissues. It can be broadly categorised into two types, with both types exhibiting different characteristics and treatment options.

Tobacco smoking is undeniably the leading cause of lung cancer. Cigarette smoke contains more than 7000 chemicals, many of which are carcinogens that damage lung tissues and DNA. Smokers are 15 to 30 times more likely to develop lung cancer than non-smokers.

The use of other tobacco products, such as cigars or pipes, also substantially increases the risk of developing lung cancer.

While the primary risk factor for lung cancer is tobacco smoking, several surprising causes have emerged in recent years. Here are some of the lesser-known factors that can cause its onset.

Types of lung cancer

Non-Small Cell Lung Cancer (NSCLC) accounts for between 80 and 85 per cent of all cases of lung cancer. It is further divided into three types:

• Adenocarcinoma is the most prevalent form of NSCLC and usually originates in the outer regions of the lungs. It is often seen in non-smokers and affects both young and older individuals.
• Large-cell carcinoma. This type of cancer is extremely metastatic and is characterised by large, abnormal-looking cells.
• Squamous cell carcinoma usually originates in the bronchial tube linings and is frequently associated with smoking.

Small Cell Lung Cancer (SCLC) makes up almost 15 per cent of all lung cancer cases and is strongly associated with smoking. While it is more responsive to chemotherapy than NSCLC, it tends to grow and spread quite rapidly.

Risk factors

Secondhand smoke

Secondhand smoke, also known as passive smoking or environmental tobacco smoke, refers to the inhalation of smoke produced by the burning of tobacco products such as cigarettes by someone else.

Inhaling the smoke emitted from other people’s tobacco products poses a significant risk, causing lung cancer, cardiac diseases, and even death, especially if there is prolonged exposure.

According to the WHO, non-smokers who live with smokers are at increased risk of smoking-related illnesses, with the risk of coronary heart disease and lung cancer increasing by 25 to 30 per cent and 20 to 30 per cent, respectively.

Radon gas

Radon is a radioactive gas formed as a byproduct of the decay of uranium in the environment, predominantly in rocks and soil. Prolonged exposure to high levels of radon is a significant risk factor for lung cancer.

However, the average concentration of radon in Australian homes is low and is about one-quarter of the worldwide average. Consequently, there is little cause for concern that the health of the population is at undue risk from radon in homes.

Air pollution

Worldwide, long-term exposure to outdoor air pollution, including nitrogen and sulphur gases and particulate matter, causes more than 16 per cent of all lung cancer deaths. This number comes up to 62,000 deaths every year, with individuals residing in highly polluted areas, particularly large urban cities, facing a higher likelihood of developing lung cancer.

Lung scarring

Pulmonary fibrosis is a condition characterised by the scarring of lung tissue.

According to a study conducted on lung cancer patients over a period of five years, lung scarring increases the risk of developing lung cancer, however, the exact mechanisms linking the two conditions are still being studied.

Beta-carotene

Taking beta-carotene supplements may cause lung cancer, especially in individuals who smoke or have been exposed to asbestos. The Cancer Council of Australia states that there is a convincing association between beta-carotene supplements and an increased risk of lung cancer in current smokers.

Another study, popularly known as the Beta-Carotene and Retinol Efficacy Trial (CARET) conducted on more than 18,000 heavy smokers, stated that those who took 20mg of beta-carotene daily for five to eight years had an 18 per cent greater risk of lung cancer.

Poor dietary habits

Studies show that a diet with a high glycemic index, caused by an excessive intake of saturated fats and processed meats, is associated with a significant increase of lung cancer risk.

Hormones

Recent research suggests that having high levels of testosterone in the bloodstream, particularly in men and postmenopausal women who use hormone contraceptives or progesterone-containing hormone replacement therapy (HRT), might play a role in the development or progression of lung cancer.

Do you smoke? Did you know about these possible causes of lung cancer? Let us know in the comments section below.

Also read: Can this vitamin help prevent cancer?

Disclaimer: This article contains general information about health issues and is not advice. For health advice, consult your medical practitioner.