KEY POINTS:
Like most cancers, prostate cancer can be unpredictable.
What can appear to be a slow growth can change quickly, complicating - if not completely altering - treatment.
A long-term study by researchers at Otago University's Wellington School of Medicine hopes to change that, allowing for doctors to better
predict a cancer's progress, and better target treatment for the most common cancer among New Zealand men.
The Radar project will assemble the world's biggest library of prostate cancer cell data.
"We're going to develop a much better understanding about the nature of an individual's cancer," said Associate Professor David Lamb, leading the study.
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"The appearances under the microscope are very important in predicting how a cancer will behave. The appearances can vary from a fairly indolent type of cancer, right up to something that is very, very aggressive.
"There are shades along the way, and it's important to be able to pick up these subtle differences that suggest the behaviour will be more aggressive than you might have believed.
"At the end of the day we want to tailor the treatment to match the disease."
At the moment, doctors recommend a watchful wait in some cases where the tumour appears slow growing, largely because of the patient's age and the potential side-effects of treatment, which could include incontinence or impotence.
"We can't predict the exact course of someone's illness. We do know that for low-risk prostate cancers, if we do nothing, half of the patients will have died of prostate cancer within 15 years.
"That is really the decision the patient needs to make - whether or not they want their cancer treated, and weigh that with the potential risk of getting side-effects from the treatment.
"We believe the trial is going to provide a lot of the missing information needed to look at all the tumour characteristics of a particular cancer and say, 'This requires a certain amount of treatment, and this one we can keep the treatment to a minimum'."
The study is being ntsundertaken done in more than 20 centres in Australia and New Zealand. More than 800 participants, including 175 New Zealand men, have signed up. This time next year Dr Lamb expects to have more than 1000.
As part of the trial, pathological material from the cancers of every participant will be collated and reviewed in Wellington.
"This will be the biggest prostate cancer database in the world," said Dr Lamb, who also heads the Wellington Radiation Service.
The Radar study will also look at the amount of hormone treatment to administer, and the merits of a drug, zoledronic acid.
Zoledronic acid helps to prevent the thinning of bones, a side-effect of hormone treatment in prostate cancer. But the drug has also been shown to delay the cancer's spread. The hope is that zoledronic acid will prevent prostate cancer spreading into bone.
"If it did this, it would be a major breakthrough because people don't die of prostate cancer in the prostate gland, they die when it gets away from the prostate gland, and in most instances, when it spreads, it spreads into the bone.
"If you could reduce that, you would have made significant gains in controlling the cancer," said Dr Lamb.
The future of prostate cancer treatment is likely to include gene therapy (see sidebar) and vaccines, several of which are in trials around the world.
This year the Mater Medical Research Institute in Brisbane started small-scale trials for its prostate cancer vaccine.
The vaccine uses synthetic proteins that appear similar to the largest molecules in prostate cancer cells. The hope is that by introducing them into the body, an immune response will kill cancer cells as they appear.
Significant advances are being made on the drug front.
Satraplatin, part of an older class called platinum compounds, binds to the DNA of cancer cells, making the cell incapable of dividing. The tumour stops growing and eventually dies.
Oncologist and Auckland University researcher Dr Mark McKeage said Satraplatin had demonstrated encouraging anti-tumour activity in a range of tumour types. An application to the FDA was under way.
Another bright hope is the experimental drug PR-104. Part of a new generation known as prodrugs, the cancer-killing compounds remain inert in the body until activated within a specific location, allowing for normal cells to be left unharmed.
PR-104 is in early clinical trials in Los Angeles, Melbourne and at Waikato Hospital, with results expected at year's end. It was developed at the Auckland Cancer Research Centre over 20 years.
