A simple blood test may help to improve survival rates for ovarian cancer by revealing which patients are likely to develop a resistance to chemotherapy drugs.
Professor Robert Brown, of Glasgow University in Scotland, told a cancer conference on Monday that he and his colleagues found that the body can switch off genes that enable chemotherapy to kill cancer cells if the tumor reappears after initial treatment.
The blood test would enable doctors to identify patients who are likely to respond to additional treatment following a recurrence, or those who could benefit from soon-to-be tested drugs that are designed to turn the genetic switch back on.
“It is the first time this test has been used in this manner,” Brown said in an interview.
“We’re using it in ovarian cancer patients to look at mechanisms of how tumors become resistant to chemotherapy and to show associations with patient survival following chemotherapy.”
Signs of gene methylation
Blood tests have been used in other types of cancer to detect the genetic changes, known as gene methylation, that can occur in tumors. Patients who do not acquire methlyation of a particular gene survive longer.
About 190,000 cases of ovarian cancer and 114,000 deaths occur each year. Eastern Europe, Scandinavia, the United States and Canada have the highest rates of the disease, according to the International Agency for Research on Cancer (IARC) in Lyon, France.
The five-year survival rate is about 40 percent because the illness is often not diagnosed before it has spread.
In early results from 500 ovarian cancer patients in an international trial of the test, Brown and his team found signs of gene methylation.
“We are seeing acquisition of this mechanism that switches genes off, and secondly that acquisition of the mechanism that switches genes off is associated with poorer survival in the patients,” said Brown, a molecular biologist who presented his findings at a meeting of senior researchers at the charity Cancer Research UK in Harrogate, northern England.
He added that it is important to identify patients who could benefit from new drugs, known as demethylating agents, which would be given in conjunction with chemotherapy after a relapse.
“By switching these genes back on...you will sensitize the tumors to chemotherapy,” said Brown.