( BBC ) - A vaccine for ovarian cancer has produced "encouraging" results in preliminary trials, US scientists say.
The vaccine is designed to enhance the body's own immune response to the cancer, said the Roswell Park Cancer Institute, based in Buffalo, New York.
Most patients with advanced disease respond to chemotherapy, but more than 70% die from a recurrence of the cancer within five years of diagnosis.
Cancer Research UK welcomed the study but said further trials were needed.
Details of the study appear in Proceedings of the National Academy of Sciences.
The vaccine contains an ovarian cancer protein fragment coupled with a molecule known to induce immune response.
It targets a protein produced in a high proportion of ovarian cancer cells, but not in healthy cells.
The researchers tested it in women with epithelial ovarian cancer, a cancer type that originates in the covering of the ovaries.
They said although their study was designed as a phase one clinical trial - a preliminary study - it had produced "encouraging" results.
The vaccine induced the immune system to produce antibodies, and to mobilise specialised T cells which were able to target cancer cells producing the key protein.
The researchers detected vaccine-induced immune cells in patients up to 12 months after immunisation, suggesting a long-lasting effect.
Lead researcher Professor Kunle Odunsi said: "There is now compelling evidence that the immune system has the capacity to recognise and kill ovarian cancer cells.
"Our vaccine strategy is simply taking advantage of this knowledge in an effort to improve the outcome for ovarian cancer patients.
"We are confident that the vaccine will eventually be widely available."
Dr Alison Ross, of the charity Cancer Research UK, said: "We welcome any research that could lead to improved survival for people with ovarian cancer, and cancer vaccines have exciting potential.
"This early trial shows encouraging results but it's important to remember that much larger studies will be needed before we know for sure whether the vaccine is safe and effective."