Diffusion-weighted magnetic resonance imaging for prediction of insignificant prostate cancer in potential candidates for active surveillance.

OBJECTIVES

To investigate whether the apparent diffusion coefficient (ADC) from diffusion-weighted magnetic resonance imaging (DW-MRI) could help improve the prediction of insignificant prostate cancer in candidates for active surveillance (AS).

METHODS

Enrolled in this retrospective study were 287 AS candidates who underwent DW-MRI before radical prostatectomy. Patients were stratified into two groups; Group A consisted of patients with no visible tumour or a suspected tumour ADC value > 0.830 × 10(-3) mm(2)/sec and Group B consisted of patients with a suspected tumour ADC value < 0.830 × 10(-3) mm(2)/sec. We compared pathological outcomes in each group.

RESULTS

Group A had 243 (84.7 %) patients and Group B had 44 (15.3 %) patients. The proportion of organ-confined Gleason ≤ 6 disease and insignificant prostate cancer was significantly higher in Group A than Group B (61.3 % vs. 38.6 %, p = 0.005 and 47.7 % vs. 25.0 %, p = 0.005, respectively). On multivariate analysis, a high ADC value was the independent predictor of organ-confined Gleason ≤ 6 disease and insignificant prostate cancer (odds ratio = 2.43, p = 0.011 and odds ratio = 2.74, p = 0.009, respectively).

CONCLUSION

Tumour ADC values may be a useful marker for predicting insignificant prostate cancer in candidates for AS.

KEY POINTS: • ADC from DW-MRI can help assess prostate cancer aggressiveness in potential AS candidates. • There was a closed correlation between higher ADC values and insignificant prostate cancer. • The absence of lesions on DWI/DWI can help select potential AS candidates.