Purpose: Indium 111 capromab pendetide radioimmunoscintigraphy (ProstaScint) has been used to detect occult recurrent carcinoma after radical prostatectomy.
Materials and methods: We evaluated the role of ProstaScint in 24 men with rising prostate-specific antigen (PSA) level following definitive radiation therapy to differentiate between local and distant recurrence in this patient population.
Results: ProstaScint scan detected prostatic uptake only in 16 patients, extraprostatic uptake in 5, both prostatic and extraprostatic uptake in 1, and no uptake in 2. Ten of 21 patients with prostatic uptake had positive biopsies, 5 had negative biopsies, and 6 were not biopsied. Two of the three patients with negative scans had positive biopsies, and the third patient was not biopsied. Three patients had evidence of osseous metastasis on radionuclide bone scan, two corresponding to the sites detected on ProstaScint. All three patients had abnormal uptake beyond the prostatic fossa with (n =2) or without (n = 1) prostatic uptake. There were no positive bone scans in patients without extraprostatic uptake on ProstaScint.
Conclusions: ProstaScint scan is useful in detecting occult recurrence outside the prostate in patients with rising PSA following radiation therapy. Compared to data from radical prostatectomy, ProstaScint scans in these patients reveal a higher prevalence of abnormal uptake in the prostate and less frequent extraprostatic uptake.