A new report confirms that a diagnostic scanner widely used in the United States but almost unavailable in Canada is highly effective in detecting cancers.

The report has doctors demanding that more PET scanners -- the best tool for catching certain cancers and seeing how far tumours have spread -- be purchased. There are only two of the high-tech devices available to cancer patients in Canada. There are about 250 in the United States, one expert says.

"I think this report means that there is absolutely no justification now for provincial governments to say there is no evidence for the benefit of the test," said Sandy McEwan, head of the Canadian Association of Nuclear Medicine.

"It validates the use of PET in all the other countries that are using it extensively," said Dr. McEwan.

The machines are commonly used in Germany and Japan.

"In the United States now it would be regarded as malpractice not to do a PET scan on somebody suspected of possibly having a lung cancer," said Dr. McEwan, who is also an oncologist at the Cross Cancer Institute in Edmonton.

PET -- Positron Emission Tomography -- scans use radioactive pharmaceuticals to detect cancer tumours and have not been found to have side effects.

The report from the Institute for Clinical Evaluative Sciences was prepared for the Ontario Ministry of Health, the Ontario Hospital Association and the Ontario Medical Association. It reviewed international research on PET scans from 1975 to 2001.

Patients with lung cancer, colon cancers, cancers in the head and neck, advanced breast cancer, lymphoma and melanoma can avoid some surgeries and invasive tests by having the scan, the report says.

For example, PET scans are 93% accurate in detecting the spread of lung cancer, compared with 63% for CT scans, according to the report.

At a cost of between $1.5-million and $3-million per machine, plus hundreds of thousands of dollars to maintain each year, provincial governments have been slow to adopt the new technology. The authors of the report did not make any recommendations for the purchase of new PET scanners.

"Having a PET scan available for some patients would be beneficial. But the health care system is so strapped now, there is a huge number of priorities out there right now besides PET scanning," said Andreas Laupacis, lead author of the study.

However, doctors say the information provided by the scanners allows them to avoid unnecessary surgeries.

"If a patient has lung cancer, we would send that patient to surgery, which is expensive and painful. But if the PET scan shows the cancer has spread and the patient would not be a good candidate for surgery, we could send them instead to radiotherapy, sparing the patient unhelpful therapy, getting them into a better treatment quicker," Dr. McEwan said.

Lung cancer is the leading cancer in Canada, with 21,200 new cases expected to be diagnosed this year.

There are two PET scanners available to cancer patients in Canada -- one in Hamilton, Ont., and one in Sherbrooke, Que. A third will open soon in Edmonton. A private clinic in Vancouver opened last fall and charges patients about $2,500 for the test.

"We cannot make do with what we have already," said Simon Sutcliffe, president of the B.C. Cancer Agency. "PET represents state-of-the-art management. One would be functioning at less than state-of-the-art if you don't have access to PET," he said.

"We are at the very, very low end of the major economic countries in the world. We are at the bottom of the barrel basically," said Christopher O'Brien, head of the Ontario Association of Nuclear Physicians, who says the PET scanners are "gold standard treatment" throughout industrialized countries.

There are 23,500 patients in Ontario alone who could benefit from the technology, according to the report; 800 people were tested last year at the Hamilton centre.

The issue was highlighted at a recent meeting of the Society of Nuclear Medicine in Toronto, where American doctors presented dozens of new studies on research using the scans. "It was depressing for Canadian doctors," Dr. McEwan said.

Physician groups in Alberta and British Columbia have presented similar reports to their governments and one is expected soon from Quebec.