The efficacy of prognostic factors derived from Ga68-PSMA PET-CT images in predicting treatment response and survival in patients with metastatic castration-resistant prostate cancer treated with Lu-177PSMA


Oflas M., Has Şimşek D., Şanlı Y., Kuyumcu S., Işık E. G., Karadoğan S., ...More

EANM’23, Vienna, Austria, 9 - 13 September 2023

  • Publication Type: Conference Paper / Full Text
  • City: Vienna
  • Country: Austria
  • Istanbul University Affiliated: Yes

Abstract

The efficacy of prognostic factors derived from Ga68-PSMA PET-CT images in predicting treatment response and survival in patients with metastatic castration-resistant prostate cancer treated with Lu-177PSMA


Author Block: M. Oflas1, D. Has Simsek1, Y. Sanli1, S. Kuyumcu1, E. Isik1, S. Karadogan1, M. Basaran2, M. Ekenel2, A. Mudun1, Z. G. Ozkan1;
1ISTANBUL FACULTY OF MEDICINE DEPARTMENT OF NUCLEAR MEDICINE, ISTANBUL, TÜRKIYE, 2ISTANBUL UNIVERSITY INSTITUTE OF ONCOLOGY, DEPARTMENT OF MEDICAL ONCOLOGY, ISTANBUL, TÜRKIYE.

Abstract:
Aim/Introduction: We aimed to determine the efficacy of metabolic parameters obtained from Ga68-PSMA PET/CT images performed in the early period after 2 cycles of Lu177-PSMA therapy to evaluate the therapy response and prognosis in patients with metastatic castration-resistant prostate cancer (mCRPC). Materials and Methods: Patients diagnosed with mCRPC, who were treated ≥2 cycles of Lu177-PSMA treatment in our department were retrospectively examined. Metabolic tumour volume (MTV) and total lesion PSMA (TLP) values were calculated on Ga68-PSMA PET/CT images performed before and after second Lu-177 PSMA treatment. In the evaluation of treatment response, ≥30% decrease in basal MTV and TLP values was accepted as consistent with partial responsive disease (PR), ≥30% increase with progressive disease (PD), and <30% increase/decrease with stable disease (SD),respectively. ≥ 50% reduction in basal PSA value was evaluated as PR ; ≥25 % increase as PD; the remaining group evaluated as SD, respectively. In addition, information about overall survival (OS) was obtained through medical records. Results: 89 male patients were included in the study (mean age: 72 years). Pre- / post-treatment median serum PSA, MTV and TLP values are indicated in Table 1.OS was calculated as 17 months (4-55 months) from the start of Lu-177 PSMA treatment. When survival analysis is evaluated according to PSA change after 2 cycles; OS was calculated as 27 months in PR (n:40), 16 months in SD (n:20) and 10 months in PD (n:29), respectively. The differences in OS were statistically significant (p <0.001).When survival analysis is performed according to MTV values after 2 cycles; OS was calculated as 27 months in PR (n:30), 18 months in SD (n:23) and 12 months in PD (n:36), respectively. The OS differences were statistically significant (p:0.002).When survival analysis is evaluated according to TLP after 2 cycles ; OS was calculated as 20 months in PR (n:41), 13 months in SD (n:23), and 14 months in PD (n:25), respectively .The OS differences between these groups were not statistically significant (p=0.088). Conclusion: It was determined that change of MTV value obtained from Ga68-PSMA PET/CT images before and after the first 2 cycles of Lu-177 PSMA treatment was correlated with overall survival in mCRPC patients .However, change of TLP values was not correlated with overall survival .Therefore, MTV value has been found as a favorable parameter in addition to PSA in order to help the clinician for earlier evaluation of treatment response and providing prognostic information. References: none