Ten-year outcomes: the clinical utility of single photon emission computed tomography/computed tomography capromab pendetide (Prostascint) in a cohort diagnosed with localized prostate cancer.
OBJECTIVE
To evaluate the clinical utility of capromab pendetide imaging with single photon emission computed tomography coregistration with computed tomography (SPECT/CT) in primary prostate cancer (CaP) for pretreatment prognostic staging and localization of biologic target volumes (BTV) for individualized image-guided radiotherapy dose escalation (IGRT-DE).


METHODS
Patients consecutively presenting for primary radiotherapy (February 1997 to December 2002), having a clinical diagnosis of localized CaP, were evaluated for tumor stage using conventional staging and SPECT/CT (N=239). Distant metastatic uptake (mets) were identified by SPECT/CT in 22 (9.2%). None of the suspected mets could be clinically confirmed. Thus, all subjects were followed without alteration in disease management. The SPECT/CT pelvic images defined BTV for IGRT-DE (+150% brachytherapy dose) without (n=150) or with (n=89) external radiation of 45 Gy. The National Comprehensive Cancer Network criteria defined risk groups (RG). The median survivor follow-up was 7 years. Biochemical disease-free survival (bDFS) was reported by clinical nadir +2 ng/mL (CN+2) criteria. Statistical analyses included Kaplan-Meier, multivariate analysis, and Concordance-index models.


RESULTS
At 10-year analyses, overall survival was 84.8% and bDFS was 84.6%. With stratification by RG, CN+2 bDFS was 93.5% for the low-RG (n=116), 78.7% for the intermediate-RG (n=94), and 68.8% for the high-RG (n=29), p=0.0002. With stratification by pretreatment SPECT/CT findings, bDFS was 65.5% in patients with suspected mets (n=22) vs. 86.6% in patients with only localized uptake (n=217), p=0.0014. CaP disease-specific survival (DSS) was 97.7% for the cohort. With stratification by SPECT/CT findings, DSS was 86.4% (with suspected mets) vs. 99.0% (localized only), p=0.0001. Using multivariate analysis, the DSS hazard ratio for SPECT/CT findings (mets vs. localized) was 3.58 (p=0.0026). Concordance-index tests, based on all data, by CN+2 bDFS criteria were 0.710 for RG alone and 0.773 for SPECT/CT + RG.


CONCLUSIONS
Through long-term outcomes we demonstrate statistically significant bDFS and DSS predictive value for pretreatment capromab pendetide SPECT/CT imaging in primary CaP. Dual clinical utility is demonstrated, using SPECT/CT to define BTV for individualized IGRT-DE.
Department of Radiation Oncology, University Hospitals, Case Medical Center and Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA. rodney.ellis@case.edu
Rodney J
RJ
Ellis
Deborah A
DA
Kaminsky
Esther H
EH
Zhou
Pingfu
P
Fu
Wei-Dong
WD
Chen
Alaina
A
Brelin
Peter F
PF
Faulhaber
Donald
D
Bodner
D000368:Aged; D000911:Antibodies, Monoclonal; D001918:Brachytherapy / Q000379:methods; D018572:Disease-Free Survival; D006801:Humans; D007205:Indium Radioisotopes; D053208:Kaplan-Meier Estimate; D008297:Male; D015999:Multivariate Analysis; D011467:Prostate / Q000000981:diagnostic imaging*; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000000981:diagnostic imaging* / Q000473:pathology; D012044:Regression Analysis; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods
D000911:Antibodies, Monoclonal; D007205:Indium Radioisotopes; C101315:Capromab Pendetide; D017430:Prostate-Specific Antigen