br F fluorocholine which was around months but with a
18 F-fluorocholine which was around 6 months24 but with a lack of sufficient correlation with this parameter as described in previ-ous studies.25 Our results showed a high percentage of positive studies when the PSA value was less than 1 ng/ml compared with previous data with 18 F-fluorocholine (47.6% of detection vs. 30.3%, respectively),18 and few negative studies when the PSA value was greater than 1 ng/ml (13.9%). When the PSAdt was less than 6 months, we obtained a majority of positive stud-ies (13 out of 15 [86.7%]). This value was lacking in 19 patients thereby limiting its interpretation. These results might indicate that PET with 68Ga-PSMA-11 should be preferentially used com-pared to 18 F-fluorocholine in patients with a low PSA value (less than 1–2 ng/ml), thanks to its detection capacity at this threshold compared with other imaging studies and/or a low PSAdt19.
Although the multivariate analysis did not show statistical sig-nificance (p = 0.059), it KPT330 is of note that of the 19 patients who had undergone androgen deprivation, 18 (94.7%) obtained a positive result in the PET with 68 Ga-PSMA-11. This opens the opportunity for treatment aimed at oligometastatic disease in the localizations shown by this technique,12 or in selecting patients who might be candidates for treatment with Lutetium-177.6,26
A recent study showed that in the biochemical recurrence of prostate cancer, PET with 68 Ga-PSMA-11 can modify the therapeutic approach in 54% of the patients undergoing this procedure.27 This retrospective study lacks sufficient follow-up data for comparing this finding, but the high rate of detection of pathological findings in patients in whom other
diagnostic strategies had been exhausted suggests that PET with 68 Ga-PSMA-11may have a great impact on clinical management.
One of the limitations of this study is that taking into account the retrospective nature of the study and the usual disease man-agement, in which images with a high probability of disease are sufficient for urologists and oncologists to implement or change a treatment, there is no gold standard such as histopathological analysis to verify the results. Thus, an analysis of validity such as the predictive capacity of the diagnostic test was not performed, but rather conditions or parameters associated with positive results with PET/CT with 68 Ga-PSMA-11 were identified. However, in other studies in which a histopathological correlation was made, verifica-tion of the 68 Ga-PSMA-11 findings9 seem to surpass those obtained with 18 F-fluorcholine.23 Nonetheless, data are lacking in the liter-ature, since in addition, synaptic cleft are difficult to corroborate in small sized lesions.28
In conclusion, our study confirms that PET with 68 Ga-PSMA-11 has a high detection rate in patients with previous doubtful or negative results in other imaging techniques. Other radio-tracers do not have sufficient sensitivity in patients with low PSA levels; however, in the present study, PET with 68 Ga-PSMA-11showed active disease in almost 50% of the patients with biochemical recurrence of prostate cancer and PSA lev-els < 1 ng/ml.
The present study was not funded by a specific grant from any public, commercial or charitable organizations.
Conflict of interests
The authors declare no conflict of interest.
2. Bouchelouche K, Tagawa ST, Goldsmith SJ, Turkbey B, Capala J, Choyke P. PET/CT imaging and radioimmunotherapy of prostate cancer. Semin Nucl Med. 2011;41:29–44.
3. Osborne JR, Akhtar NH, Vallabhajosula S, Anand A, Deh K, Tagawa ST. Prostate-specific membrane antigen-based imaging. Urol Oncol Semin Orig Investig. 2013;31:144–54.
5. Cunha AC, Weigle B, Kiessling A, Bachmann M, Rieber EP. Tissue-specificity of prostate specific antigens: comparative analysis of transcript levels in prostate and non-prostatic tissues. Cancer Lett. 2006;236:229–38.
7. Von Eyben FE, Kairemo K. Acquisition with 11C-choline and 18F-fluorocholine PET/CT for patients with biochemical recurrence of prostate cancer: a systematic review and meta-analysis. Ann Nucl Med. 2016;30:385–92.
9. Afshar-Oromieh A, Zechmann CM, Malcher A, Eder M, Eisenhut M, Linhart HG, et al. Comparison of PET imaging with a (68)Ga-labelled PSMA ligand and (18)F-choline-based PET/CT for the diagnosis of recurrent prostate cancer. Eur J Nucl Med Mol Imaging. 2014;41:11–20.
10. Eder M, Neels O, Müller M, Bauder-Wüst U, Remde Y, Schäfer M, et al. Novel preclinical and radiopharmaceutical aspects of [68 Ga]Ga-PSMA-HBED-CC: a new PET tracer for imaging of prostate cancer. Pharmaceuticals. 2014;7:779–96.
13. Sheikhbahaei S, Afshar-Oromieh A, Eiber M, Solnes LB, Javadi MS, Ross AE, et al. Pearls and pitfalls in clinical interpretation of prostate-specific mem-brane antigen (PSMA)-targeted PET imaging. Eur J Nucl Med Mol Imaging. 2017;44:2117–36.