Evaluating the Prognostic Impact of Apparent Diffusion Coefficient in Definitive Radiotherapy for Gleason Score 7...

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Gleason score (GS) 7 prostate cancer (PCa) presents a challenge for treatment stratification.
• Diffusion-weighted magnetic resonance imaging (DW-MRI) is a promising tool for non-invasive tumor evaluation.
• Understanding the role of DW-MRI in GS 7 tumors is crucial for optimizing radiotherapy (RT).

Purpose of the Study:

• To assess the utility of DW-MRI in evaluating GS 7 PCa before RT.
• To correlate apparent diffusion coefficient (ADC) values with clinicopathological factors.
• To explore the association between tumor ADC values and treatment outcomes (biochemical disease-free survival [bDFS] and prostate cancer-specific survival [PCSS]).

Main Methods:

• Retrospective analysis of 266 PCa patients with biopsy-confirmed GS 7 undergoing RT.
• Measurement of primary tumor ADC values using pretreatment DW-MRI.
• Statistical analysis to correlate ADC values with clinicopathological factors and survival outcomes.

Main Results:

• GS 3+4 tumors showed significantly higher ADC values than GS 4+3 tumors (p < 0.001).
• Lower tumor ADC values correlated with higher GS and increased risk of progression.
• An ADC cutoff of 0.682 × 10⁻³ mm²/s predicted disease progression; higher ADC values predicted better 7-year bDFS (92.8% vs. 83.2%, p = 0.02).
• GS 4+3 tumors independently predicted poorer bDFS and PCSS.

Conclusions:

• Tumor ADC values reliably differentiate between GS 3+4 and 4+3 tumors within the GS 7 category.
• Lower ADC values are associated with higher risk factors and increased likelihood of disease progression.
• DW-MRI, through ADC values, can aid in risk stratification and treatment planning for GS 7 PCa.