2307 CORRELATION OF INDIUM-111 CAPROMAB PENDETIDE SPECT/CT TO SOFT TISSUE HISTOPATHOLOGY IN PROSTATE CANCER

INTRODUCTION AND OBJECTIVES: Indium-111 capromab pendetide SPECT/CT has become an increasingly important tool in the management of prostate cancer on account of its ability to accurately detect soft tissue metastases. Yet, only a few studies have been published regarding its diagnostic role in localized disease. In order to gain a more comprehensive understanding of its absolute utility, we have determined the diagnostic performance of In-111 capromab pendetide in associated soft tissues via correlation to a gold standard of histopathology. METHODS: In this retrospective study, all In-111 capromab pendetide SPECT/CT scans acquired at our institution were reviewed for dedicated histopathology within a four-month period. Statistical measures of performance were calculated in terms of glandular, seminal vesicle and lymph node activity. The accuracies of glandular and seminal vesicle activity were then correlated to the indices of risk and treatment history. RESULTS: A total of 200 scans met the criteria of our study. Of them, 197 had prostate gland histopathology and 94 had bilateral seminal vesicle histopathology for comparison. An additional five scans had a total of 43 lymph nodes for comparison. The statistical measures of performance are summarized in Table 1. For glandular activity alone, scan accuracy was found to significantly improve with increasing Gleason score (p 0.0001). The scans demonstrating discordant results were broadly associated with low to intermediate grade tumors. Furthermore, the glandular scan accuracy was significantly increased in setting prior to treatment (91%, p 0.0005). After treatment the accuracies ranged from 54.5-66.7%. No statistically significant differences were found between the groups with regards to seminal vesicle activity. CONCLUSIONS: The results of this study further validate the role of In-111 capromab pendetide in diagnosing lymph node metastases from primary cancers of the prostate, but also demonstrate the test may have limited utility in diagnosing tumors within the seminal vesicles. In terms of glandular activity, further studies are needed regarding its utility for noninvasive grading of primary tumors, and as a component in clinical management algorithms.