Radiotherapy is a commonly used cancer treatment
A gene which hinders the ability of radiotherapy to kill cancer cells has been detected by UK researchers.
The team found that if they blocked the POLQ gene - which has a role in repairing damaged DNA - radiotherapy was more effective.
It is hoped that the discovery, which came about after a trawl through 200 candidate genes, could lead to new drugs to boost radiotherapy.
The findings are published in the journal Cancer Research.
Many thousands of cancer patients will have some form of radiotherapy as part of their treatment, and it is estimated to contribute to 40% of cases where cancer is eliminated.
The researchers from the University of Oxford said tumours can differ widely in the way they respond to radiotherapy - but the reasons for these differences are largely unknown.
In order to find a potential target for increasing the chances that radiotherapy would work, they looked specifically at genes involved in repairing DNA damage.
After pinpointing the POLQ gene, they found that blocking it in several different types of cancer cell in the laboratory, including laryngeal and pancreatic tumours, rendered the cells more vulnerable to the effects of radiation.
Previous research had shown that the POLQ gene is not particularly active in normal healthy tissue.
Doing the same experiment in healthy cells, the team found that blocking the gene did not have any effect on the sensitivity of normal tissue to radiation.
The researchers said the fact that the POLQ seemed to more abundant in cancer cells than normal cells made it a good target for boosting the effects of radiotherapy.
Study leader Dr Geoff Higgins, a Cancer Research UK scientist at the Gray Institute for Radiation Oncology and Biology, said: "We've sieved through a vast pool of promising genetic information and identified a gene that could potentially be targeted by drugs to improve the effectiveness of radiotherapy.
"Blocking the activity of this gene resulted in a greater number of tumour cells dying after radiotherapy and provides new avenues for research."
Professor Gillies McKenna, director of the institute, added: "The next stage is to translate this discovery into a treatment that will benefit patients."