It is billed as the test to scare smokers into quitting - a personalised genetic check of your chances of getting lung cancer.

But now some public health groups question the test's safety, saying it may perversely encourage some to keep on puffing.

An Auckland University scientist, Associate Professor Robert Young, has commercialised a genetic test for lung cancer risk.

And in a new finding, he has confirmed the long-suspected genetic cross-over between smokers' susceptibility to lung cancer, and to another potentially fatal lung condition - chronic obstructive pulmonary disease (COPD or emphysema).

Smokers who want to check their risk of lung cancer can phone Dr Young's company Synergenz and pay $275 to join the testing programme, or sign up though a medical clinic for $75, in addition to the GP's fees.

The smokers take genetic samples from inside their cheeks by swab. These are checked for 20 genetic variations linked with lung cancer risk.

The results are considered with factors such as age and prior lung disease to rank smokers as being of moderate, high or very high risk of developing lung cancer.

The test can now also be used to rank patients for risk of emphysema.

Half of severe cases of emphysema die within five years of diagnosis, as do 85 to 90 per cent of people diagnosed with lung cancer.

the lung cancer survival rate is 80 per cent when the disease is picked up early, but people usually don't seek help until the disease is established.

Dr Young said yesterday that smokers understanding their disease risks by using his test, called Respiragene, might help prevent some cases of smoking-related lung disease because several preventive drugs were being tested in advanced clinical trials.

A more immediate benefit is that the test results appear to shock many into quitting.

A small study by Synergenz found the quit rate among people tested was more than 30 per cent, against 5 per cent among smokers who received no support or personal risk information.

But Respiragene has attracted public health criticism in the US and now in New Zealand because of fears that being listed at the lower end of the scale of lung cancer risk might give a false sense of safety to some smokers.

The Action on Smoking and Health director, Ben Youdan, said the test results could act as a "green light to smoking - when there is no safe level of smoking".

Those identified as high-risk by Respiragene testing have a four-fold higher risk of developing lung cancer than the average smoker.

But average smokers are 20 to 30 times more likely than non-smokers to develop lung cancer.

Auckland University tobacco researchers found some Pacific smokers do not accept that smoking causes lung cancer and can kill.

* 80 per cent of people could survive lung cancer.
* 85-90 per cent die because it is not detected early enough.
* New genetic test can detect chances of developing the disease.
* Anti-smoking groups believe it could encourage complacency among smokers.