Can ⁶⁸Ga-PSMA-11 Positron Emission Tomography/Computerized Tomography Predict Pathological Response of Primary Prostate Cancer to Neoadjuvant Androgen Deprivation Therapy? A Pilot Study.

Abstract

We explored the role of ⁶⁸Ga-PSMA-11 positron emission/computerized tomography as a predictor of pathological response to neoadjuvant androgen deprivation therapy combined with abiraterone for high risk prostate cancer. A total of 45 patients with localized high risk prostate cancer who had serial ⁶⁸Ga-PSMA-11 positron emission tomography/computerized tomography scans before and after 6 months of androgen deprivation therapy plus abiraterone neoadjuvant treatment followed by radical prostatectomy were included in this study. Complete pathological response or minimal residual disease <5 mm on whole mount histopathology was defined as favorable pathological response. The diagnostic performance of prostate specific antigen response and positron emission tomography/computerized tomography response for favorable pathological response was calculated. Univariable and multivariable logistic regression analyses of clinical and imaging variables were also performed to identify favorable pathological response. Compared to the prostate specific antigen response, positron emission tomography/computerized tomography response had a significantly higher specificity in diagnosing favorable pathological response (89.7% vs 62.1%, p=0.043). Preoperative nadir prostate specific antigen (OR 0.121, 95% CI 0.028-0.529, p=0.005), posttreatment maximum standardized uptake value (OR 7.072, 95% CI 2.035-24.579, p=0.002) and posttreatment tumor volume (OR 7.896, 95% CI 1.415-44.054, p=0.018) measured on positron emission tomography/computerized tomography were significantly associated with favorable pathological response in univariable logistic regression analysis. On multivariable logistic regression analysis, only posttreatment maximum standardized uptake value was found to be an independent predictor of favorable pathological response (OR 9.69, 95% CI 1.439-65.242, p=0.020). ⁶⁸Ga-PSMA positron emission tomography/computerized tomography has a better diagnostic performance of pathological response to neoadjuvant treatment compared with prostate specific antigen, with maximum standardized uptake value being an independent predictive factor. This pilot study suggests that prostate specific membrane antigen positron emission tomography/computerized tomography may serve as a potential predictor of pathological response to neoadjuvant treatment.