Vaccine may halt prostate cancer
In a major breakthrough, British scientists have already demonstrated that the vaccine works in a large percentage of patients.
The vaccine is a ray of hope for men whose prostate cancer has advanced to the stage where it becomes immune to hormone treatment.
At this point, known as hormone relapse, a patient's life expectancy can be as little as one or two years.
Prostate cancer is almost as common among men as breast cancer in women. According to the Irish National Cancer Registry, it kills around 500 men each year and the number of cases diagnosed has increased from 1,378 in 1999 to 1,570 last year.
The vaccine was developed from cultured tumour cells and given to 28 patients at St George's Hospital Medical School in London.
All the men taking part in the on-going phase two trial had hormone relapsed prostate cancer (HRPC), but the disease had not yet spread into their bones, one of the last stages before death.
The patients were vaccinated with a combination of three laboratory-grown prostate cancer cell lines every month for a year.
Prostate cancer can be tracked by measuring the level of the PSA protein, which is released by the prostate gland.
The release of PSA normally accelerates as the cancer takes hold but for 30% of the patients receiving the vaccine, the rate of PSA release slowed significantly.
Patients who responded had lasted more than 50 weeks without the disease progressing, compared with about 20 weeks for untreated patients.
Those who showed significant drops in PSA reading also produced a "very pronounced" increase in levels of two important immune system chemical messengers. This indicated that their bodies were fighting the cancer.
The researchers now plan to proceed to large scale phase three trials the last stage before a drug is put on the market in the next 12 to 18 months.
The Irish National Cancer Registry (NCRI) said the new development was positive but cautioned that new vaccines did not always turn out to be as effective as originally thought.
There are conflicting views about the effectiveness of early screening for prostate cancer.
NCRI Director Dr Harry Comber advised men to talk to their doctor.
"They should go with an open mind and ask their GP about screening. There may be certain men in certain risk groups for whom it would be a good idea," he said.
