Evaluation of whole-body tumor burden with 68Ga-PSMA PET/CT in the biochemical recurrence of prostate cancer

Background68Ga-PSMA-PET has an increasing importance in the evaluation of prostate cancer patients due to its high sensitivity and specificity in identifying neoplastic lesions in the clinical setting of elevated prostate-specific antigen (PSA). The objective of this study was to calculate the whole-body tumor burden using volumetric quantification of lesions detected in Ga-68-PSMA-PET of prostate cancer patients with biochemical recurrence and correlate these findings with clinical and image parameters.MethodsEach patient had their Ga-68-PSMA-PET analyzed for the presence of neoplastic lesions. Their PSA levels and clinical information were recorded. In positive cases, the tumor burden (TL-PSMA) was calculated with a semi-automatic software and manually, and the results are analyzed and tested.ResultsWe analyzed 100 prostate cancer patients, mean age of 69.99.7years and a median PSA of 1.73ng/dL. Ga-68-PSMA-PET identified neoplastic lesions in 72% of them. The median TL-PSMA was 55.95ml (1.1-28,080ml). TL-PSMA and PSA were strongly correlated (rho=0.71, p<0.0001, 95% CI 0.60-0.80). TL-PSMA and PSA levels groups had a significant correlation and TL-PSMA and Gleason score were independent variables associated with PSA levels (p<0.05).Conclusion TL-PSMA strongly and independently correlates with PSA levels in prostate cancer patients and could be used as a biomarker to separate them into groups with high or low tumor burden, instead of considering only the number of lesions.