Gallium-68 DOTATOC PET/CT in vivo characterization of somatostatin receptor expression in the prostate

The aim was to investigate somatostatin receptor (sstr) expression in normal prostate by determining the maximum standardized uptake value (SUVmax) of (68)Ga-DOTATOC PET/CT in neuroendocrine tumor (NET) patients, without NET involvement of the prostate gland, for establishing the reference standard.

Sixty-four NET patients underwent (68)Ga-DOTATOC PET/CT. SUVmax of the prostate gland, normal liver, testes, and gluteus muscles were evaluated. The prostate gland size was measured. Statistical analysis was performed using dedicated software (SPSS13).

Mean/median (68)Ga-DOTATOC SUVmax values were as follows: normal prostate 2.6 ± 0.0, slightly enlarged prostate 4.2 ± 1.6, prostatic hypertrophy 4.9 ± 1.6, prostatic hyperplasia 5.0 ± 1.5, prostate cancer 9.5 ± 2.1, normal liver 7.3 ± 1.8, testes 1.8 ± 0.5, and gluteus 1.0 ± 0.2. The normal prostate gland had three times less sstr expression than normal liver tissue. Strong correlation was found between patient age and sstr expression in prostate/prostate size. No significant difference existed in sstr expression between prostatic hypertrophy and hyperplasia. Much higher sstr expression was found in prostatic cancer compared with normal prostate.

(68)Ga-DOTATOC PET/CT defines the baseline sstr uptake in prostate not affected by NET (significantly lower than in the liver). Higher values were established in prostatic hyperplasia and hypertrophy. Only concomitant prostate cancer was associated with higher SUVmax in comparison with non-neoplastic liver.