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Multiparametrik MR ile prostat görüntülemesi, prostat biopsisi ihtiyacını azaltabilir mi?

Can Imaging Replace Biopsy for Some Prostate Cancer?

Kate Johnson

April 24, 2014

STOCKHOLM — A picture might one day spell relief for men who currently have to undergo prostate biopsy to investigate possible signs of cancer, according to preliminary results from a new trial.

The PICTURE trial is comparing 2 different imaging technologies — multiparametric (mp)MRI and HistoScanning (Advanced Medical Diagnostics) — with transperineal template-guided prostate mapping biopsy, which served as the reference biopsy.

Results from a planned interim analysis were presented here at the European Association of Urology 29th Annual Congress.

"We think that mpMRI might be a useful test at this point in the diagnostic pathway, and its encouraging negative predictive value may allow men to safely avoid biopsy," said lead researcher Lucy Simmons, MD, from University College, London in the United Kingdom.

However, HistoScanning "did not perform well at all for this," she told Medscape Medical News.

Session chair Boris Hadaschik, MD, from the University of Heidelberg, Germany, agreed, noting that the results show that "HistoScanning is of very limited value."

Although HistoScanning, which uses raw ultrasound data, is not available in North America, it is used routinely in parts of Europe and at some trial centers in the United Kingdom. "It is available in Germany and people are spending money on it, but I think recent publications show that it's not very good," Dr. Hadaschik added.

Can Imaging Prevent Another Biopsy?                    

The interim analysis involved 114 men who had already undergone 1 transrectal ultrasound (TRUS)-guided biopsy but required further investigation to rule out clinically significant prostate cancer. The median age of the cohort was 63 years.

"Some men had no disease on TRUS, but their PSA was still high; others had disease that was low volume and we thought that was out of keeping with their PSA," Dr. Simmons reported. "The aim was to see if either or both modalities would be useful in preventing further biopsies. They've had 1 biopsy — can we prevent another by doing one of these tests?"

All men underwent mpMRI and HistoScanning in addition to the reference biopsy to evaluate the ability of each imaging modality to rule out significant prostate cancer, defined as a Gleason score of 4+3 or a maximum cancer core length of 6 mm.

Whole gland analysis using mpMRI produced promising results, with an area-under-the-curve of 0.78 for the detection of clinically significant disease, a sensitivity of 69%, a specificity of 78%, a positive predictive value of 67%, and a negative predictive value of 79%.

In contrast, HistoScanning displayed high sensitivity (84%), but poor specificity (6%) and poor positive and negative predictive values (37% and 36%, respectively).

The final results could reveal even poorer results for HistoScanning, Dr. Simmons noted.

"There is a slight learning curve with MRI, which means the MRI may not have performed as well in these first men as it will in the overall cohort, so the final MRI results might be even better," she explained.

Earlier studies showing promise for HistoScanning were based on a different population. "Previous studies looked mainly at radical prostatectomy cohorts, where all men were known to have cancer. In this study, some men have cancer and some don't, and the burdens of disease are different," Dr. Simmons noted. "HistoScanning also doesn't have any way of differentiating grade of disease — everything is based on size — so if some patients' disease is small, HistoScanning doesn't do well. I think that's what's reflected in this study."

"The PICTURE trial is an excellent study, and we're all looking forward to the final results," Dr. Hadaschik told Medscape Medical News.

"The aim in the future would be that if MRI does not show anything, you can avoid the biopsy, but we need studies like PICTURE to be able to evaluate the risk of that approach," he explained. "Here it's showing that MRI is excellent but not perfect; there are some tumors that will be overlooked. This is probably not a problem because you can decrease overdiagnosis and then follow-up with the patient a year later. It's probably safe to treat that tumor a year later."

Dr. Simmons and Dr. Hadaschik have disclosed no relevant financial relationships.                    

European Association of Urology (EAU) 29th Annual Congress: Abstract 951. Presented April 14, 2014.

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