Correlación entre el volumen molecular tumoral evaluado con PET/TC con 68Ga-PSMA y los niveles de antígeno prostático específico / Correlation between molecular tumor volume evaluated with 68Ga-PSMA PET/CT and prostatic specific antigen levels

Objetivo: Investigar la asociación entre el nivel del antígeno prostático específico (PSA) en el mismo momento de la realización de PET/TC con 68Ga-PSMA y el volumen tumoral metabólico (MTV) en pacientes con cáncer de próstata en progresión bioquímica. Métodos: En este análisis retrospectivo se estudió a 84 pacientes sometidos a PET/TC con 68Ga-PSMA, a quienes se midieron los niveles de PSA en la misma semana (Trigger-PSA). Se calculó el MTV a partir de la suma de las lesiones metastásicas. Para determinar las relaciones entre el nivel de Trigger-PSA y los hallazgos de PET/TC utilizamos la correlación de Spearman. Resultados: El MTV medio de la enfermedad ósea (mBD) fue significativamente superior al valor encontrado en los ganglios metastásicos (mLN) (139,5 frente a 17,7; p<0,05). La enfermedad se limitó a la próstata en 8 pacientes (9,5%), mLN en 21 pacientes (25%), mBD en 32 pacientes (38,1%) y las 3 localizaciones (próstata, mBD y mLN) en 17 pacientes (20,2%). En 6 pacientes (6,14%), la PET/TC con 68Ga-PSMA no fue capaz de detectar la enfermedad. Los niveles medios de Trigger-PSA en los pacientes con enfermedad limitada a próstata (2,8ng/ml), mLN (6,8ng/ml) y mBD (16,8ng/ml) fueron estadísticamente significativos (p<0,05). Los pacientes positivos tuvieron un Trigger-PSA medio de 4,3ng/ml frente a 1,5ng/ml en los pacientes negativos (p<0,05). Establecimos 3 puntos límite para la tasa de detección del nivel de Trigger-PSA:≤1ng/ml (47,3%), 1-4ng/ml (68,4%) y≥4ng/ml (96,7%). Cuando el Trigger-PSA excedió de 4ng/ml, el MTV fue superior (p<0,001). Conclusión: Los resultados evidencian la correlación de MTV con Trigger-PSA, lo cual puede tener impacto sobre el tratamiento. Sin embargo, los niveles de Trigger-PSA no permitieron distinguir entre la enfermedad localizada o a distancia. La estadificación precisa de la enfermedad podría permitir planificar la mejor estrategia terapéutica

Objective: To investigate the association between prostatic-specific antigen (PSA) levels and molecular tumor volume (MTV) measured in the 68Ga-PSMA PET/CT, both done in a short period of time, in prostate cancer patients with biochemical failure. Methods: Eighty-four patients who underwent 68Ga-PSMA PET/CT and measurement of PSA levels in the same week (trigger-PSA) were studied in this retrospective analysis. MTV was calculated from the sum of the metastatic lesions. To determine the association between trigger-PSA level and PET/CT findings, Spearman rank correlation was used. Results: The median MTV of metastatic bone disease (mBD) was significantly higher than in metastatic lymph-nodes (mLN) (139.5 versus 17.7; P<.05). Disease was limited to the prostate in 8 patients (9.5%), mLN in 21 patients (25%), mBD in 32 patients (38.1%) and the 3 sites (prostate, mLN, and mBD) in 17 patients (20.2%). In 6 patients (6.14%), 68Ga-PSMA-PET/CT was not capable of detecting disease. The median trigger-PSA levels of patients with disease limited to the prostate (2.8ng/mL), mLN (6.8ng/mL), and for mBD (16.8ng/mL) was statically significant (P<.05). Positive patients had a mean trigger-PSA of 4.3ng/mL vs 1.5ng/mL in negative patients (P<.05). We established 3 threshold-points for trigger-PSA level detection rate:≤1ng/mL (47.3%), 1-4ng/mL (68.4%) and≥4ng/mL (96.7%). When trigger-PSA exceeded 4ng/mL, the MTV was higher (P<.001). Conclusion: The correlation of MTV with trigger-PSA is demonstrated, which may have an impact on management. However, trigger-PSA levels were not capable of distinguishing between localized or distant disease. An accurate detection of disease can lead to a better therapeutic strategy

Correlation between molecular tumor volume evaluated with 68Ga-PSMA PET/CT and prostatic specific antigen levels. / Correlación entre el volumen molecular tumoral evaluado con PET/TC con 68Ga-PSMA y los niveles de antígeno prostático específico.

OBJECTIVE: To investigate the association between prostatic-specific antigen (PSA) levels and molecular tumor volume (MTV) measured in the 68Ga-PSMA PET/CT, both done in a short period of time, in prostate cancer patients with biochemical failure. METHODS: Eighty-four patients who underwent 68Ga-PSMA PET/CT and measurement of PSA levels in the same week (trigger-PSA) were studied in this retrospective analysis. MTV was calculated from the sum of the metastatic lesions. To determine the association between trigger-PSA level and PET/CT findings, Spearman rank correlation was used. RESULTS: The median MTV of metastatic bone disease (mBD) was significantly higher than in metastatic lymph-nodes (mLN) (139.5 versus 17.7; P<.05). Disease was limited to the prostate in 8 patients (9.5%), mLN in 21 patients (25%), mBD in 32 patients (38.1%) and the 3 sites (prostate, mLN, and mBD) in 17 patients (20.2%). In 6 patients (6.14%), 68Ga-PSMA-PET/CT was not capable of detecting disease. The median trigger-PSA levels of patients with disease limited to the prostate (2.8ng/mL), mLN (6.8ng/mL), and for mBD (16.8ng/mL) was statically significant (P<.05). Positive patients had a mean trigger-PSA of 4.3ng/mL vs 1.5ng/mL in negative patients (P<.05). We established 3 threshold-points for trigger-PSA level detection rate:≤1ng/mL (47.3%), 1-4ng/mL (68.4%) and≥4ng/mL (96.7%). When trigger-PSA exceeded 4ng/mL, the MTV was higher (P<.001). CONCLUSION: The correlation of MTV with trigger-PSA is demonstrated, which may have an impact on management. However, trigger-PSA levels were not capable of distinguishing between localized or distant disease. An accurate detection of disease can lead to a better therapeutic strategy.