Do low-tar cigarettes put women more at risk of aggressive lung cancer?

The number of people diagnosed with lung cancer is growing in the world. In the UK, the number affected has risen by 13 per cent over the past decade, according to Cancer Research UK. This year, death rates from lung cancer among European women are set to overtake those for breast cancer, according to a study of cancer rates in 28 EU countries published last week.

Researchers from the University of Milan, who carried out the study, say the trend is largely due to women in the UK and their long history of smoking. But cancer experts are quick to point out that occasional smokers and even non-smokers are also at risk.

Ian Hunt, a consultant thoracic surgeon at St George's Hospital in Tooting, says: 'Decades ago, we saw a rise in more women smoking. While in recent years that number has decreased, particularly among middle-aged women, smoking among young women is still quite prevalent.'

Another change is in the type of cigarettes people smoke. When Marion did smoke, she tended to choose extra-mild, low-tar varieties. Mr Hunt says: 'Many people, especially women, have moved on to low-tar cigarettes in the mistaken belief they're better for them - but there is some evidence to suggest that people inhale these more deeply than they would a stronger cigarette in order to get the same effects. This has led to a change in the types of cancer we now see.'

The two types of lung cancer most often seen in the UK are squamous cell carcinoma (usually found in the centre of the lung) and adenocarcinoma (the type diagnosed in Marion, and often found in the outer areas of the lungs).

In recent years, surgeons like Mr Hunt have seen a rise in adenocarcinoma, which is the most common lung cancer in women - possibly as they inhale low-tar cigarettes more deeply - and in non-smokers, though experts are unclear why.

'People think of lung cancer as a smoker's disease and there's this idea that if you stop smoking, your risk of lung cancer somehow decreases back to the level of someone who never smoked at all.

'In fact, that doesn't happen. It's simply not true to assume that risk is eliminated once you stop smoking.' Nor is it simply that heavy smokers are most at risk. 'The truth is, we just don't know why some people smoke heavily for years and never get lung cancer, while some occasional smokers do.'