Clinical Significance of the Apparent Diffusion Coefficient Ratio in Prostate Cancer Treatment with Intensity-modulated Radiotherapy.

AIM: We aimed to investigate the correlation between biochemical recurrence (BCR) and the pretreatment apparent diffusion coefficient (ADC) ratio of tumor to normal prostate tissue in patients with prostate cancer who underwent intensity-modulated radiotherapy (IMRT).

PATIENTS AND METHODS: Retrospective analyses were performed for 101 patients diagnosed with localized prostate cancer who underwent IMRT at a dose of 70-78 Gy to the prostate gland and medial part of the seminal vesicles. Before treatment, all patients underwent magnetic resonance imaging including diffusion-weighted imaging of the prostate. BCR was defined as a rising prostate-specific antigen level (the Phoenix criterion).

RESULTS: The median follow-up for all patients was 29 months, and BCR occurred in 10 patients (9.9%). ADC ratios and Gleason scores were significant independent prognostic factors of BCR by multivariate analysis.

CONCLUSION: The pretreatment ADC ratio was an independent prognostic factor for BCR in patients with prostate cancer who underwent IMRT.