A new pill has shown promise of reducing the risk of death from lung cancer by half, according to results of a decade-long global clinical trial.

Taking the drug osimertinib, developed by AstraZeneca, after surgery dramatically reduced the risk of patients dying by 51 per cent, showed results presented at the American Society of Clinical Oncology's (Asco) annual meeting in Chicago.

Osimertinib, which is marketed as Tagrisso, targets a particular type of lung cancer in patients suffering from non-small cell cancer -- the most common type -- and shows a particular type of mutation.

Lung cancer is the world's leading cause of cancer death, accounting for about 1.8 million deaths a year.

"Thirty years ago, there was nothing we could do for these patients," said lead author Dr Roy Herbst, the deputy director of Yale Cancer Center, was quoted as saying by the Guardian.

"Now we have this potent drug. Fifty per cent is a big deal in any disease, but certainly in a disease like lung cancer, which has typically been very resistant to therapies."

The trial involved patients aged between 30 and 86 in 26 countries and looked at whether the pill could help non-small cell lung cancer patients.

Everyone in the trial had a mutation of the EGFR gene -- which is found in about a quarter of global lung cancer cases -- and accounts for as many as 40 per cent of cases in Asia. An EGFR mutation is more common in women than men, and in people who have never smoked or have been light smokers.

As per the study's findings, more people diagnosed with lung cancer must be tested for the EGFR mutation.

The pill proves to be "practice-changing" and should become the "standard of care" for the quarter of lung cancer patients worldwide with the EGFR mutation, Herbst said.

"This further reinforces the need to identify these patients with available biomarkers at the time of diagnosis and before treatment begins."

After five years, 88 per cent of patients who took the daily pill after the removal of their tumour were still alive, compared with 78 per cent of patients treated with a placebo, the report said.