Prognostic value of FDG, PSMA, and DOTATATE uptake on PET imaging in metastatic castration-resistant prostate cancer (mCRPC).

Author(s): Frederic Pouliot1; Fred Saad2; Étienne Rousseau3; Patrick O. Richard4; Atefeh Zamanian1; Stephan Probst5; Eric Levesque1; Vincent Castonguay6; Nicolas Marcoux7; Daniel Juneau8; Michele Lodde9; Jean-Baptiste Lattouf10; François-Alexandre Buteau11; Zineb Hamilou12; Michel Pavic13; Jean-François Castilloux13; Guillaume Bouvet11; Amélie Tetu14; Brigitte Guérin3; Jean-Mathieu Beauregard11
Maem Hussein MD

Dr. Maen Hussein's Thoughts

It might be costly to get the PET scans but helps with prognosis and directing patients to palliative care since positive lesions in all predicts shorter overall survival.


In mCRPC, fluorodeoxyglucose (FDG) and prostate-specific membrane antigen (PSMA) PET/CT are often used in combination for selecting patients for PSMA-radioligand therapy (PSMA-RLT). Few studies have specifically assessed the prognostic value of FDG+/PSMA- lesions, which exclude patients from PSMA-RLT. Also, little is known about the significance of somatostatin receptor expression, a potential biomarker of neuroendocrine differentiation of mCRPC, which can be assessed with DOTATATE-PET/CT. 3TMPO is a prospective study in progressing mCRPC patients who were imaged with up to 3 PET tracers. Here, we report on patient’s overall survival (OS), with respect to the presence of FDG+/PSMA- and DOTATATE+ lesions.


In 3TMPO (NCT04000776, protocol in PMID 34674367), all patients had 68Ga-PSMA-617 and 18F-FDG PET/CT scans. A 68Ga-DOTATATE scan was ordered if an FDG+/PSMA- lesion was found. For all tracers, positivity was defined as lesion SUVpeak being 1.5x higher than liver SUVmean. Kaplan-Meier with log-rank test was used to assess the difference in OS between groups. Cox regression model was used to quantify the effect of factors predictive of OS.


The median [95% CI] OS of the 98 enrolled patients was 10.2 [8.5-11.8] mo. At least one FDG+/PSMA- lesion was found in 45 (45.9%) patients and their OS was shorter than that of the others: 5.6 [4.3-6.9] vs. not reached (p=0.0001). Six (16.2%) of 37 patients who underwent 68Ga-DOTATATE-PET had ≥1 DOTATATE+ lesion and their OS was shorter than that of patients without a DOTATATE+ lesion: 3.0 [2.2-3.7] vs. 6.4 [1.6-11.1] mo. (p=0.0004). Characteristics significantly associated with worse OS were ECOG, ISUP grade, number of metastases, number of lines of therapy, presence of visceral metastases, FDG and PSMA molecular tumor volumes (MTV) (p<0.05). In a multivariate analysis adjusted for the number of metastases and of treatment lines, the presence of an FDG+/PSMA- lesion increased the risk of death (HR [95% CI]=2.4 [1.4-4.3], p=0.002), and this was also significant after adjusting for both PSMA and FDG-MTV (HR [95% CI]=2.9 [1.4-5.8], p=0.003).


mCRPC patients harboring FDG+/PSMA- lesion(s) had a shorter OS than those who did not, and their prognosis was even poorer if they also had DOTATATE+ lesion(s). Upfront FDG/PSMA-PET followed by DOTATATE-PET might help clinicians to guide patient towards palliative care vs. further systemic therapy, including PSMA-RLT.

Author Affiliations

1CHU de Québec – Université Laval, Québec, QC, Canada; 2Centre Hospitalier de l’Université de Montréal, Université de Montréal, Montréal, QC, Canada; 3CIUSSS de l’Estrie – CHUS (Hôpital Fleurimont), Sherbrooke, QC, Canada; 4CIUSSS de l’Estrie – CHUS (Hôpital Fleurimont), Sherbrooke, QC, Canada; 5Jewish General Hospital, Montréal, QC, Canada; 6CHU de Québec – Hotel Dieu de Québec, Québec, QC, Canada; 7Hotel Dieu de Quebec, Quebec, QC, Canada; 8Centre Hospitalier de l’Universite de Montreal, Montreal, QC, Canada; 9Centre Hospitalier Universitaire Pavillon l’Hôtel-Dieu de Québec, Québec, QC, Canada; 10Centre Hospitalier de l‘Université de Montréal/CRCHUM, Montreal, QC, Canada; 11CHU de Québec – Université Laval, Québec, QC, Canada; 12Centre Hospitalier de l’Université de Montréal, Montreal, QC, Canada; 13CIUSSS de l’Estrie- CHUS (Hôpital Fleurimont), Sherbrooke, QC, Canada; 14CIUSSS de l’Estrie – CHUS, Sherbrooke, QC, Canada

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