Experts say some diagnostic techniques which could help detect the cancer at an early stage, are not available in the UK because of cost.

Five year survival rates for men have fallen from 6% in the early 70s to 5% in the early 90s.

For women, rates remained constant at around 5%.

Lung cancer is still the commonest cause of cancer death in the UK for both men and women.

The results of the Finnish study, whilst encouraging for the relatively small group investigated, do not unfortunately reflect survival figures in the UK

Sara Hiom, Cancer Research UK

Finnish researchers followed 600 patients, with an average age of 67, diagnosed with lung cancer in Oulu, in the north of Finland.

An earlier study, carried out 20 years before, had followed 446 patients from the same area for four years.

Between the two studies, five year survival rates increased from 4% to 12%, despite the fact that the population in the second study was older.

Variations between cancers

Dr Riitta M�kitaro who led the study said: "This evaluation stands out very clearly and is really the main message of our study."

However, the researchers admit that this increase is only an average, and survival rates vary between different types of lung cancer.

The rate for adenocarcinoma is now almost five times higher than 20 years ago (19% compared with 4%), although the proportion of this type of cancer has increased, now accounting for almost one lung cancer in five.

But two-year survival rates for small cell carcinoma, which also accounts for about a fifth of all lung cancers, are only slightly better, increasing to 19% from 14% 20 years ago, the researchers found.

They added that in patients whose cancers had spread beyond the lung, were unlikely to survive for more than three years.

They stress early diagnosis, when the tumour is small and has not spread, offers the best chance of survival.

Treatments such as using new fibre optic bronchoscopy and medical imaging techniques, have meant earlier and more precise diagnosis and better accuracy in determining what stage the disease stage has reached.

The chances of survival improve with surgery, with the research showing 48% of those patients who have surgery survive for more than five years, compared to 23% 20 years ago.

Survival chances

Doctors can now better evaluate which patients would benefit from surgery, increasing survival chances.

Dr M�kitaro said: "Basically, whenever the disease is diagnosed early, it can be treated more effectively and the chances of survival improve."

But Sara Hiom, science information officer for Cancer Research UK told BBC News Online: "The results of the Finnish study which suggest a tripling of survival rates for lung cancer, whilst encouraging for the relatively small group investigated, do not unfortunately reflect survival figures in the UK.

She added: "Clearly, improvements in diagnostic techniques do pave the way for increased survival rates through earlier diagnosis.

"However, techniques such as spiral CT scanning � which has been shown in studies, both in the USA and Japan, to be more effective than X-ray in detecting lung tumours earlier � are not readily available in the UK due to economic restraints."