Growing numbers of non-smokers are being diagnosed with lung cancer, many at a stage when it is incurable, experts in the disease have revealed.
They blame the rise on car fumes, secondhand smoke and indoor air pollution, and have urged people to stop using wood-burning stoves because the soot they generate increases risk.
About 6,000 non-smoking Britons a year now die of the disease, more than lose their lives to ovarian or cervical cancer or leukaemia, according to research published on Friday in the Journal of the Royal Society of Medicine.
That is about a sixth of the 36,000 deaths a year from lung cancer.
“If considered as a separate entity, lung cancer in never-smokers is the eighth most common cause of cancer-related death in the UK and the seventh most prevalent cancer in the world,” the authors state.
A “never-smoker” is classed as someone who has smoked fewer than 100 cigarettes in their lifetime.
The authors include Prof Paul Cosford, Public Health England’s director for health protection and medical director, and Prof Mick Peake, the director of the centre for cancer outcomes at University College London hospitals.
“With declining rates of smoking, the relative proportion of lung cancers in never-smokers is rising,” they said. “In addition, the absolute numbers and rates of lung cancers in never-smokers are increasing.”
Cosford – himself a non-smoker with lung cancer – said: “People will find these numbers very surprising. They rarely think of lung cancer as a non-smoker’s disease. They’re so focused on smoking as the main risk factor that we forget that there are quite a few causes of lung cancer that affect non-smokers.
“From a personal perspective, when I knew I was ill I never thought I would have lung cancer as I wasn’t a smoker. There’s an emerging realisation that this is a health problem we need to get supportive about.”
The difficulty identifying lung cancer means that many non-smokers are diagnosed when it has reached stage three or four, which means that treatment may prolong their life, but they cannot be cured.
Patients are often misdiagnosed, especially by GPs, and have their symptoms mistaken for something else, such as muscular pain, partly because they are similar to those for other ailments.
Breathing in secondhand smoke – for example being brought up in a home where one or both parents smoke – is the single biggest risk factor for a non-smoker getting lung cancer, the paper says. That accounts for 15% of the 6,000 cases.
Exposure to carcinogens in the workplace, such as asbestos, are to blame for 20.5% of lung cancers in non-smoking men and 4.3% in non-smoking women.
Outdoor air pollution is also a key factor, accounting for 8% of cases in non-smokers. It is thought to lead directly to the death of 39,000 Britons every year from a range of medical conditions, including lung cancer.
Wood and coal-burning stoves used indoors are also a risk, added Cosford. “I would like a nice wood-burning stove and used to have one. But we can’t get away from the fact that we are producing air pollution by burning wood and coal in our houses.
“The best thing is not to do it, but if you do do it then use the latest technology stove, use seasoned wood and have good ventilation.”
Richard Steyn, a consultant thoracic surgeon in the NHS and the chair of the UK Lung Cancer Coalition, said: “Apart from avoiding passive smoke, areas of high air pollution and wearing protective breathing apparatus in specific occupations, there is not a great deal that someone who does not smoke can do to avoid the risk.”
Health professionals need to be more aware that a non-smoker could have lung cancer in order to improve earlier diagnosis, he added.
“GPs and hospital doctors working in the NHS need to be more aware of the fact that lung cancer does occur in people who have never smoked and that as a disease in itself is more common than many other cancers that have a much higher profile, such as cancers of the cervix, ovary and the leukaemias.
“Many patients who have never smoked who develop lung cancer have their diagnosis delayed because of this lack of recognition so many of them have very advanced disease by the time they get to specialist care.”