Diffusion-weighted MRI could stratify prostate cancer treatment options

Diffusion-weighted (DW)-MRI noninvasively detects significant prostate cancer with high probability without the use of contrast medium or an endorectal coil and could be used as a tool to stratify patients with prostate cancer for individualized treatment options, according to a study published online March 15 by the Journal of Urology

A reliable, noninvasive diagnostic tool is needed to distinguish between tumors that require treatment and the rest in patients with prostate cancer. Because recent literature has proposed use of functional MRI techniques, including DW-MRI, to fit this bill, lead author Lauren J. Bains, MSc, PhD, of the University of Berns in Switzerland, and colleagues prospectively assessed the diagnostic accuracy of DW-MRI for detection of significant prostate cancer.

The study group included 111 consecutive men with prostate and/or bladder cancer who underwent 3 Tesla DW-MRI of the pelvis without an endorectal coil. A total of 78 patients underwent the examination before radical prostatectomy and 33 before cystoprostatectomy. Three readers were blinded to clinical and pathological data that were assigned to a prostate cancer suspicion grade based on qualitative imaging analysis. The reference standard was based upon final pathology results of prostates with and without cancer.

DW-MRI indicated prostate cancer in 93 patients from the study group. The cancer was significant in 80 patients and insignificant in 13. Another 18 showed no sign of prostate cancer on final pathology results. The data also revealed that prostate cancer detected at systematic biopsy was under graded in 20 out of 78 patients. The sensitivity and specificity of DW-MRI for detecting significant prostate cancer for the readers was 89 percent to 91 percent and 77 percent to 81 percent, respectively. The researchers determined that interreader agreement was good. Median reading time was found to be between 13 and 18 minutes.

“The advantage of DW-MRI alone is the fact that this technique is less expensive, faster and easier to interpret,” wrote Bains et al. “Therefore, it could be applied to broader clinical settings, including larger patient populations.”

The authors emphasize the need to validate the technique using final pathology results of prostates with and without cancer as the reference standard by conducting larger scale studies.

“[DW-MRI] may improve patient stratification for individualized treatment options, eg by discriminating tumors requiring curative treatment from those that may benefit from expectant management. It might be even used as a first line screening tool in the future," they concluded.