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MRI-based predictors of treatment failure in intermediate-risk prostate cancer treated with high-dose-rate
Jacob F Oyeniyi1, Joseph S Lee1, Chen Shen1
1Department of Radiation Oncology, Corewell Health William Beaumont University Hospital, Royal Oak, MI.
Objective:
To identify MRI features associated with treatment failure in intermediate-risk prostate cancer patients treated with HDR brachytherapy monotherapy.
Methods:
We analyzed 115 men with intermediate-risk prostate cancer who underwent definitive HDR brachytherapy as monotherapy and had pretreatment MRI within 6 months. MRI features assessed included lesion size, focality, location, capsular contact (yes vs. no, with no gross extracapsular extension), length of capsular contact, and PIRADS score. Univariable and multivariate logistic regression analyses were performed to identify MRI features associated with treatment failure, defined as biochemical recurrence and/or local recurrence.
Results:
The median age was 64 years, and median pretreatment PSA 5.95 ng/mL; 49 patients had favorable and 66 had unfavorable intermediate-risk disease. At 47 months median follow-up, 19 patients (16.5%) experienced treatment failure. MRI features associated with treatment failure on UVA included lesion size (OR: 3.9, CI: 1.8-8.8, p < 0.001), multifocality (OR: 2.9, CI: 1.0-7.9, p = 0.043), capsular contact (OR: 64.3, CI: 8.1-510.0, p < 0.001), capsular contact length ≥1 cm (OR: 5.0, CI: 1.6-15.7, p = 0.006), and PIRADS 5 (OR: 16.7, CI: 2.7-324.8, p = 0.011). On MVA, only capsular contact remained significant (OR: 57.2, CI: 9.5-106.2, p < 0.001). In patients with capsular contact (n = 39), ADT significantly reduced treatment failure (OR: 0.101, CI: 0.002-0.912, p = 0.023).
Conclusion:
Capsular contact on MRI is a strong independent predictor of treatment failure in intermediate-risk prostate cancer patients undergoing HDR brachytherapy as monotherapy. The addition of ADT significantly decreased the odds of treatment failure in these patients. These findings highlight the value of MRI-based risk stratification and suggest that treatment intensification options such as ADT could be considered to optimize treatment outcomes.
