13 NOVEMBER 2018

Lung Cancer: Deadly But Largely Preventable

Parkway Cancer Centre’s Dr Patricia Kho discusses how lung cancer can be largely preventable, if only people stopped smoking.

One of the most lethal forms of cancer – lung cancer – is at the same time one of the most preventable. Why? Because the link between tobacco use and lung cancer has been studied extensively over several decades and proven.

Tobacco use reportedly causes 90 per cent of lung cancer in men and 79 per cent in women. The risk of lung cancer development is between 20 and 40 times higher in lifelong smokers compared with non-smokers.

So the most obvious way to prevent lung cancer is not to smoke. Studies have found that after a person has stopped smoking, the cumulative death risk from lung cancer decreases. Across the globe, smoking cigarettes is estimated to cause one in three adult deaths by 2025. By that year, tobacco would kill an estimated 10 million people worldwide every year.

How common is lung cancer in Singapore?

Lung cancer is the second most common cancer among men and the third highest among women.

Over a period of five years from 2011 to 2015, more than 7,100 people in Singapore were diagnosed with lung cancer, according to statistics from the Singapore Cancer Registry. That’s about 1,400 people a year or about four every day. Men in Singapore are three times more prone to getting lung cancer than women.

How lethal is lung cancer?

Lung cancer is one of the most deadly cancers, with very low survival rates globally.

The fatality rate among lung cancer patients in Singapore is also very high – it is the leading cause of cancer death among men and the second highest among women.

Even though lung cancer patients constitute 11 per cent of all cancers in Singapore, it accounts for 22 per cent of cancer deaths, according to the Singapore Cancer Registry.

This is largely due to the fact that patients do not experience any symptoms in the early stages of the disease resulting in most lung cancers being diagnosed only at a later stage when the disease is already at an advanced stage. Most lung cancer patients in Singapore are diagnosed when they are above the age of 65.

Some of the common symptoms of lung cancer – such as cough, hoarse voice and shortness of breath – are common symptoms of other illnesses and may not immediately prompt patients or doctors to call for further checks.

How does smoking cause cancer?

Smoking tobacco damages our DNA, including some of the key genes that protect the body against cancer.

Of the thousands of chemicals in cigarette smoke, about 60 are known to cause cancer and about 200 are poisonous.

Common chemicals found in cigarettes such as benzene, polonium-210, benzo(a)pyrene and nitrosamines have been shown to cause DNA damage.

Other chemicals in cigarettes may exacerbate the problem. For example, chromium makes benzo(a)pyrene stick more closely to DNA, raising the chances of serious DNA damage.

Other chemicals such as arsenic and nickel also interfere with the body’s natural methods of repairing damaged cells, leaving them more prone to turning cancerous.

What other types of cancer are linked to smoking?

Smoking does not just cause lung cancer.

The use of tobacco has been linked to different types of cancer as well as other diseases relating to the heart and lungs. Smoking does not just affect the lungs as the chemicals in the smoke also enter a person’s blood stream, which can then affect the whole body.

Smoking also increases the risk of at least 14 other types of cancer including cancers of the mouth, pharynx (upper throat), nose and sinuses, larynx (voice box), oesophagus (gullet), liver, pancreas, stomach, kidney, bowel, ovary, bladder, cervix, and some types of leukaemia. Smoking could increase the risk of breast cancer, but any increase in risk is likely to be small.

Can non-smokers get lung cancer?

While a majority of lung cancer patients are smokers, it is a myth to think that non-smokers are immune to it. Unfortunately, about one in four lung cancer patients have never smoked before.

Prolonged exposure to certain harmful chemicals such as radon, asbestos, arsenic, chromium, nickel and even air pollutants are contributing factors to lung cancer. Those whose family members have had lung cancer are also at a slightly higher risk.

Passive smoking – where a non-smoker inhales smoke from a nearby smoker – is also harmful. When a person smokes, he or she inhales only 15 per cent of the smoke, releasing 85 per cent into the surroundings. Second-hand smoke is particularly bad for young children and pregnant women, and could cause health issues in newborns.

Many studies have shown that passive smoking can increase a non-smoker’s chances of getting lung cancer by 25 per cent.

However, in a large proportion of non-smokers with lung cancer, the cause remains unclear.

Quitting Smoking

In addition to reducing the risk of lung cancers and other cancers, smoking cessation also decreases the risks of many types of stroke, heart attacks and chronic lung diseases within one short year.

We should encourage our loved ones and friends to seek help to kick the habit and to remind others that it is a harmful habit!

Smoking: The facts

  • By 2025, smoking will cause 1 in 3 adult deaths around the world, and tobacco will kill 10 million people each year.
  • Lung cancer is the second most common cancer among men and third among women in Singapore.
  • Smoking doesn’t just cause lung cancer. It also raises the risk of at least 14 other types of cancer.
TAGS cancer fact, common cancer, lung infection, misconceptions, prevent cancer, reduce cancer risk