Robert Young: Only one way to cut lung cancer risk

Opinion

Tobacco use and nicotine addiction are enormously important public health issues that warrant a broad-based counterattack.

Tobacco control strategies that include targeted smoking bans, public messaging and higher taxation are the cornerstone of the public health approach and have been shown to help bring smoking rates down.

However, is this public health approach the only effective way to help smokers quit and prevent premature death or prolonged disability? The answer is no.

The cornerstone of prevention of coronary heart disease, another public health issue, has been through risk assessment by the measurement of cholesterol levels prompting appropriate lifestyle change.

Through this personalised risk-based approach, rather than the broad messaging of public health (eating well and exercising regularly), mortality from coronary heart disease has been drastically reduced.

The lung cancer susceptibility test (Respiragene) mentioned recently is based on important clinical variables and genetic markers which have been linked to an increased risk of lung cancer.

The test's ability to identify those smokers at greatest risk has passed peer-review and scientific scrutiny.

I believe it is useful for all smokers because it reminds them that lung cancer is an important complication of smoking that they should be worried about.

There is no "green light" for smokers taking this test - only a "red light" or "red card". The message for all smokers is that they are all at risk of lung cancer and quitting smoking is the single best thing they can do to reduce that risk.

This does not suggest that lung cancer is the only life-threatening complication of smoking but certainly one of the most common (it affects 15 per cent of all smokers) and most lethal complications (80 per cent of those with lung cancer are dead within two years after diagnosis).

The suggestion that smokers receiving a "low risk" result (score) might encourage them to continue smoking is neither supported by the scientific literature nor is it the experience of those who have trialled this or similar tests in smokers.

Such a suggestion is inaccurate on many levels. First, there is no "low risk".

The results from this test assign smokers to lung cancer risk levels of moderate, high or very high.

Moderate approximates the average smoker's risk (20 times the lung cancer risk of a non-smoker), while those at high and very high risk are 4-10 times the average risk.

There is no "safe level of smoking" and the only people assigned a "low risk" status for lung cancer are lifelong non-smokers.

Regardless of the risk level after Respiragene testing, all smokers are recommended to quit to reduce their risk.

Second, there is no evidence that smokers testing at "moderate risk" may take this as a "green light" to keep smoking.

Such a suggestion ignores the fundamental challenge for smokers, namely their addiction to nicotine and denial of the risks from smoking.

Such claims assume smokers are ignorant, unaware of other important life-threatening complications of smoking apart from lung cancer (eg, heart disease, stroke and a host of other cancers) and not the experience of those of us who help smokers quit.

The scientific literature on these issues is clear - most smokers want to quit and are looking for reasons and help to do so.

The last and most compelling reason why Respiragene is not a "green light to smoking" is that our research and the scientific literature simply do not support this view.

In a randomised trial published in a peer-reviewed journal, it was found that a lung cancer risk test based on a single gene reported quit rates of over 20 per cent greater than achieved in those who were not tested for their risk of lung cancer.

Martin Johnston in his article reports the results of a pilot study by our group showing that among randomly recruited smokers who took the Respiragene test, 32 per cent of them had quit six months later.

Importantly, we found that the proportion who quit was spread across the different risk groups and "moderate risk" smokers were not discouraged from quitting.

These findings are the subject of a second larger study which if confirmed, would make the Respiragene test one of the most cost-effective smoking cessation approaches.

To substitute the results of research and published peer-reviewed science with mere opinion and conjecture is surprising, if not irresponsible.

In assessing the clinical merits of the Respiragene test, I suggest putting the "public health" approach (and opinion) to one side.

If one reviews the clinical experience of risk-based disease prevention (a la coronary heart disease) and the results of peer-reviewed scientific research (genetic risk testing increases quitting), then it is reasonable to conclude that the Respiragene test is a valuable tool in the effort to help smokers quit.

Dr Robert Young is associate professor of medicine and molecular genetics at the University of Auckland. The science underpinning the Respiragene test has been undertaken by Dr Young and his group over the past 12 years.