Cancer Research UK says that smoking can cause up to 15 types of cancer, such as cancer of the lungs and larynx, and 15% of smokers are likely to get the disease.
But alarming statistics show that 10 to 15% of non-smokers are likely to get cancer too, especially women. How is this possible?
A non-smoker is classified as someone who has either never smoked or who has smoked fewer than 100 cigarettes in their lifetime, but they are the ones most affected by second-hand smoke that cigarette users leave behind.
“While this is a pervasive problem, some of the biggest causes of lung cancer aren’t associated with cigarettes,” says Dr Charleen Muller, a clinical and radiation oncologist at Cancercare’s East London Oncology Centre.
The causes of lung cancer
So, if smoking isn’t the only cause of lung cancer, what else should we be careful of? Dr Muller says we are currently exposed to significantly more air pollution than in the past – recent studies show that pollution caused by traffic has increased by more than 20% over the last 15 to 20 years.
And you’re not only at risk while sitting in traffic – the rise in nitrogen oxides also poses a risk to people who live near high-volume roads, or people who run in busy areas. She says runners are better off training indoors on a treadmill or going to a park.
Pollution in the air
“In addition to car and cigarette smoke, lungs are subjected to compounds such as chromium and arsenic in the manufacturing and car paint industries. These toxic compounds increase the risk of lung cancer as they cause mutations to the tissue. One of the most notorious causes of lung disease and cancer is asbestos – a group of minerals used in the building industry. Although most buildings have had the material removed, it still remains a concern for those who work in or around asbestos infected areas,” explains Dr Muller.
Other environmental risks include exposure to asbestos, chromium, arsenic elements found in solvents, thinners, paints and building materials.
Pollution you can control
You are also at risk of inhaling toxic fumes if you are exposed to wood stoves, coal fires and even braai smoke. “This is controversial, however,” says Dr Muller. “But there is an increased exposure to particulate matter and poly hydrocarbons with paraffin and coal fires and these are known to be carcinogens. In large amounts with chronic exposure they significantly increase the risk.”
Fortunately the occasional braai is not a problem. “It’s the persistent close exposure to the smoke associated with the social gathering that is a braai is the problem,” she says. “If you are right in the 'midst' of the fire for example.” So make sure you take regular breaks away from the fire.
Dr Muller also says lung cancer can be caused by previous lung disease, such as emphysema, or prior exposure to radiation of the lung areas, such as Hodgkin lymphoma treatment and breast cancer radiation. Patients being treated with radiation for Hodgkin lymphoma have a 2.6-7 times higher relative risk of developing lung cancer, which lasts for 20 to 25 years; while breast cancer radiation increases a person’s risk by about 2.3 times compared to those who haven’t had radiation.
“These stats are based on studies done with conventional radiation,” says Dr Muller. “Fortunately with the newer techniques that we use to deliver radiation the risk is much less.”
Some causes are out of most people’s control, like genetics and previous bouts of cancer. Dr Muller says there is some research into how lung cancer could be hereditary based on specific genetic markers, but currently it is in the early stages and more studies are needed to prove it definitively. Unfortunately, for those who have undergone chemo or radiation therapy, the risk of lung cancer is increased. Some chemo drugs cause scarring in the lung tissue or abnormalities which predispose them to lung cancer in the future.
Warning signs from your lungs
Dr Muller says there are five warning signs you should not ignore – rather see your doctor and get checked out:
1. If the nature of your cough changes
2. New onset of a cough
3. You are coughing up blood
4. Significant unexplained weight loss (at least 10% of your body weight)
5. Any new lumps or bumps on your body
Now for some good news
But it isn’t all bad news. “Leading a healthy life, getting exercise and avoiding the risks as much as possible will go a long way towards healthy lungs. And, perhaps most importantly, stop smoking as that not only damages your lungs, but those of everyone around you,” says Dr Muller.