LONDON -- British scientists announced a breakthrough in lung cancer research on Tuesday, identifying a molecule that may be responsible for the spread of a deadly form of the disease that kills 10,000 people in Britain each year.

According to researchers at Hammersmith Hospital and Imperial College London who published a study in the European Molecular Biology Organization's*** EMBO**** journal, the discovery is a first step toward developing a treatment for small cell lung cancer.

The particularly virulent form of cancer kills 97 percent of patients within five years of diagnosis and is often resistant to chemotherapy, thereby making treatment difficult.

The molecule, a member of the PI3K (phosphoinositide 3-kinase) family, may be crucial to the spread of the disease, the researchers said, since it influences several growth factor signals that cause cancer cells to spread and divide, AFP reported.

The scientists found that in small lung cancer cells, compared to normal lung tissue, there was too much of the molecule. Michael Seckl of Hammersmith Hospital, who led the research, called the work "an important discovery that will help us in working toward a treatment that targets and destroys the molecule and in so doing, stops cancer of the lung growing."

He said it was an "important step forward" to be able to identify a common single molecule within each cancer cell that allows the different growth factors to function.

Because small-cell lung cancer can spread in response to many growth factors, targeting individual factors on their own is not likely to be very successful. Given the dangers of the disease, Seckl said, "we are desperate to identify new therapies." "Discovering what this molecule does is a major step toward developing treatment that targets it directly and may help future generations of patients."

The study was partly funded by Cancer Research UK.