Effect of Androgen Deprivation Therapy on the Results of PET/CT with 18F-Fluciclovine in Patients with Metastatic Prostate Cancer
Round 1
Reviewer 1 Report
Authors report their experience about the use 18F-Fluciclovine PET in patients submitted to ADT for a relapsing prostate cancer. There are two major concerns
1) The majority has a detectable PSA (> 0.5 ng/mL) notwithstanding the therapy. Therefore, the study is circumscribed to a specific population, namely hormone refractory metastatic prostate cancer patients. It should be underlined in the paper.
2) Authors findings are interesting since 18F-Fluciclovine PET has an overall 82% detection rate. However, since the patients have never stopped therapy and since there is no comparison group, it is difficult to assess the real impact of ADT on the detection rate. It should be included in the discussion and in the conclusion section of the paper
3) Finally, we do not have enough evidence to suggest to stop or not to the ADT therapy. Indeed it is a reasonable "good clinical practice" not to discontinue in this particular setting since the detection rate is indeed high
Author Response
From the recommendations of reviewer 1 we have made the following additions to the manuscrtipt.
In the introduction §2, we have added
.... established, and in particular, not in patients with castration-resistant prostate cancer.
Under discussions we have added:
The most important limitation of this retrospective study was that we were not able to compare 18F-fluciclovine PET studies in patients on ADT and after withdrawal. It is thus uncertain if an interruption of ADT would have allowed an even higher detection rate.
And in the conclusion we have changed the final sentence: Indeed it is a reasonable "good clinical practice" not to discontinue ADT in this particular setting since the detection rate is already very high, insted of . However, a prospective study where the findings with 18F-fluciclovine PET before and after withdrawal of ADT in the same patients is warranted.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The paper deals a current topic and the aim is extremely interesting.
In the light of new trend in prostate cancer imaging, data about effects of ADT therapy on PET results could be extremely useful.
The work present a satisfactory structure but there are several limitations, already highlighted by the authors in discussion, that affect his own newly and quality.
The number of patients is limited causing not very incisive conclusions. The authors have to deepen the discussion about the already existing data of comparison with PSMA-tracers. This aspect may be much more interesting in a current discussion than thje comparative data presented on Choline-PET.
Nevertheless is interesting the discussion and commentary about the clinical implication of the presented data especially referring on unnecessary withdraw ADT before PET-imaging. It could be interesting to extend this study to other tracers and to compare imaging results before and after withdrawal of different categories of ADT. Satisfactory images and tables.
Author Response
We found the comments from reviewer 2 interesting and inspiration for further research.
We have added another reference with regards to ADT and PSMA, and a comment from this publication.
With the European association of Urology guidelines suggesting PSMA-imaging with biochemical recurrence at PSA levels above 0.2 ng/ml, there is less or no need for upstart of ADT therapy before an eventual PSMA PET (18).
- Vaz S, Hadaschik B, Gabriel M, et al. Influence of androgen deprivation therapy on PSMA expression and PSMA-ligand PET imaging of prostate cancer patients. Eur J Nucl Med Mol Imaging 2020; 47: 9-15.
Round 2
Reviewer 1 Report
The paper has been correctly amended by the Authors.
Author Response
Thank you.
Tore Bach-Gansmo
Reviewer 2 Report
It may be useful to review the English language and to integrate the actual bibliography
Author Response
Dear colleague.
We believe MPDI will perform an ultimate English check. Hence we believe your final comments will adhered to.
Yours sincerely
Tore Bach-Gansmo
