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

Abstract

Background

68 Ga-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 ⁶⁸Ga-PSMA-PET of prostate cancer patients with biochemical recurrence and correlate these findings with clinical and image parameters.

Methods

Each patient had their ⁶⁸Ga-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.

Results

We analyzed 100 prostate cancer patients, mean age of 69.9 ± 9.7 years and a median PSA of 1.73 ng/dL. ⁶⁸Ga-PSMA-PET identified neoplastic lesions in 72% of them. The median TL-PSMA was 55.95 ml (1.1–28,080 ml). 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.

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