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Linking real-time ultrasound to MRI may aid prostate cancer assessment

There is hope for change with a new imaging technique, often referred to as fusion biopsy, that links an MRI of the patient with images from a real-time ultrasound, allowing doctors to see suspicious areas better and target them for tissue sample testing. The development has the potential to help doctors identify aggressive forms of cancer, reduce the number of painful biopsy needles needed, and give men clearer answers sooner.

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One of the biggest challenges for urologists is distinguishing between low-risk prostate cancers and those that are aggressive enough to require treatment.

Now there is hope for change with a new imaging technique, often referred to as fusion biopsy, that links an MRI of the patient with images from a real-time ultrasound, allowing doctors to see suspicious areas better and target them for tissue sample testing.

The development has the potential to help doctors identify aggressive forms of cancer, reduce the number of painful biopsy needles needed, and give men clearer answers sooner.

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And it could help reduce the number of treatments performed on men who face no imminent risk from prostate cancer, said Tony Finelli, a uro-oncologist at the Princess Margaret Hospital Cancer Centre.

"We're trying to get out of the business of finding what someone would call insignificant, low-risk cancer," he said.

Typically, when doctors suspect a patient has prostate cancer, they take about 12 samples in an ultrasound-guided biopsy. But ultrasound cannot show the prostate in great detail, and the needles could miss cancerous areas, giving a "false negative" result. It is also painful for patients.

In fusion biopsy, an MRI gives a much more detailed picture. The radiologist flags areas of concern and the patient has an ultrasound in which the MRI image is fused aaonto the screen. This can help target areas to be biopsied, reduce the chance of a false negative, and could reduce the number of painful needles.

"It will be more effective. In other words, smaller cancer, early stage cancer will be more likely to be biopsied and diagnosed," said Aaron Fenster, chief scientific officer and director at the Centre for Imaging Technology Commercialization (CIMTEC). The centre has developed fusion imaging technology and has a spinoff company that is looking to market it.

Experts say the most reliable evidence shows that fusion biopsy is best for active surveillance – ongoing monitoring of patients who have had negative biopsies but still have elevated prostate-specific antigen (PSA) levels or other risk factors. This type of targeted screening can help reassure men who do not have an aggressive form of cancer – and help doctors spot those who do.

Rajiv Singal, a urologic surgeon at Toronto East General Hospital and assistant professor in the department of surgery at the University of Toronto, uses fusion biopsy and says it has great potential for active surveillance.

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Diagnosing prostate cancer is not an exact science.

Doctors often test the blood for elevated PSA levels. But levels can rise for many reasons, and relying on it too heavily can lead to unnecessary tests, biopsies and treatment, and side effects such as incontinence and impotence. Last month, the Canadian Task Force on Preventive Health Care released a statement arguing the risks of PSA tests outweigh the benefits. Doctors also use digital rectal exams to detect possible cases of prostate cancer, but they too can be unreliable.

Anoop Dogra, who lives in Toronto, was diagnosed with prostate cancer at 40 after a test showed elevated PSA levels and a biopsy confirmed the disease. He had surgery and recovered. He welcomes any development that could reduce the pain of a biopsy and provide more information to doctors and patients.

"If [the pain] can be minimized somehow … that would absolutely be helpful," he said.

Some companies are marketing fusion biopsy technology to health-care institutions. Dr. Singal said he and his colleagues have developed their own version, and he suspects that it will soon become the norm for active surveillance of prostate cancer.

Experts doubt it will become a standard front-line screening tool for prostate cancer because MRIs are expensive, waits can be long and the experts needed to interpret the results can be in short supply.

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About the Author

Carly Weeks has been a journalist with The Globe and Mail since 2007.  She has reported on everything from federal politics to the high levels of sodium in the Canadian diet. More

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