Can imaging improve prostate cancer characterization?

The authors examined whether a two-step approach, using imaging techniques, can accurately predict the location of a prostate tumor and how aggressive it is.

The standard way to diagnose prostate cancer is to measure prostate specific antigen (PSA: a protein produced by the prostate, with levels elevated in patients with prostate cancer), perform digital rectal examinations, and blindly take biopsies (tissue removed from a living body to discover the presence or extent of cancer).  After a biopsy is removed it can be examined under the microscope and graded. The Gleason grade describes how different the cancer cells look from normal cells and how likely it is that the tumor will spread. Although these methods are useful, more specific methods for selecting biopsies would help improve diagnosis.

It has been suggested that combining a number of imaging techniques could be useful for locating a tumor and predicting how aggressive the cancer is. Firstly, magnetic resonance imaging (MRI: uses a magnetic field and pulses of radio wave energy) can be used to create pictures of the prostate and any visible tumors. These MRI images can then be used for targeting biopsies during transrectal ultrasound imaging (TRUS imaging: an ultrasound probe is inserted into the back passage to allow imaging of the prostate gland).

This study evaluated the records of 135 prostate cancer patients (average age 64) with increased PSA levels. Each patient was firstly examined by MRI. Then the MRI results were used to guide specific biopsy removal during TRUS imaging. Finally, surgical removal of the prostate (radical prostatectomy) occurred as the primary treatment.

The authors found that MRI was good at predicting the location of the tumor and successfully located the most important tumor in 95% of the patients. In 90% of patients the Gleason score of the specifically targeted biopsy matched that of the score from the radical prostate biopsy. They also found that, in 98% of cases, the biggest tumor was also graded as the most aggressive.

The authors concluded that this technique can be used to identify the location of the most important tumor and to determine how aggressive the cancer is. 

This was a retrospective study (evaluating patient records only) which may limit how generalizable the results are.