A simple blood test could identify early-stage lung cancer, according to the results of a new study.
The test, which looked at gene activity in patients' white blood cells, achieved an accuracy rate of 87% in identifying early cancer.
Researchers at the University of Pennsylvania, USA, tried out the noninvasive technique on 44 patients with early stage lung cancer and 52 healthy volunteers.
Gene "chips", which identify active genes from their code signals, were used to identify the best targets for detecting lung cancer.
Traditionally, x-rays are used to check for lung cancer, but these produce large numbers of false positive results, which can frighten patients and result in unnecessary follow-ups and surgical procedures.
The research was presented at the American Thoracic Society's 2008 international conference in Toronto, Canada.
The leader of the study, Dr Anil Vachani, said: "These findings suggest that lung cancers interact with circulating white blood cells and change the types of genes that are active in these cells.
"A diagnostic test that could more accurately determine the risk of cancer in patients would be extremely valuable and have very important economic implications by reducing unnecessary surgery, biopsies and repeated imaging tests."