Authors: Fabio Zattoni Andrea Guttilla Laura Evangelista
Publish Date: 2016/04/23
Volume: 43, Issue: 8, Pages: 1407-1409
Abstract
In this issue of the European Journal of Nuclear Medicine and Molecular Imaging Pfister et al 1 evaluate the performance of 18Ffluoroethylcholine 18FFEC and 68GaPSMA PET/CT in patients undergoing salvage lymph node dissection sLND for recurrent prostate cancer PCa The introduction of novel imaging modalities and tracers has increased the detection of oligometastatic PCa recurrence potentially justifying the use of sLND rather than a systemic approach The present study is premised on the notion that radiopharmaceutical agents can be useful for guiding surgical procedures in cases of predominant nodal recurrence of PCa This is a topic of great interest to urologists radiologists and nuclear medicine physicians What evidence must we consider for the use of sLND Could extended LND rather than sLND during radical prostatectomy RP improve patient survival What is the best imaging modality for ensuring appropriate treatmentThese closely related questions are important because they prompt us to examine the value of clinical trials in the area of sLND in PCa The literature is lacking in both randomized trials comparing sLND with a control group treated with current best practice and prospective case–control studies evaluating the impact of PET imaging for the detection of lymph node metastases before or after RP The “scientific run” to the best imaging modality and highestperforming tracer is justified only if they provide a survival benefit and improved quality of life for patients with oligometastatic PCaIn addressing this issue therefore key points to consider in the design of future studies include 1 selection of the patient population 2 previous therapies and ongoing androgen therapy 3 extension of sLND 4 the definition of endpoints and outcomes 5 a comparison of different imaging modalities in the same population and 6 whom to randomize—for example the patients the surgeons or the imaging technologistsIn the study by Pfister et al 1 66 patients were retrospectively evaluated 38 underwent 18FFEC and 28 underwent 68GaPSMA PET/CT prior to sLND Differences between the two populations must be considered including demographic characteristics primary treatments and followup management In our opinion the selection of patients is the key driver for the trial Only patients with welldefined treatment of the primary tumor should be includedThe extension of lymphadenectomy during RP should be defined even though the role of pelvic lymph node dissection remains one of the most controversial areas in the management of clinically localized PCa However recent advances in our understanding of tumor biology and the introduction of a new PCa classification system 2 should enable better stratification of patients and should provide information about the best treatment strategya A 67yearold man with PCa treated by radical prostatectomy and lymph node dissection pT3bN1 GS 9 positive margins Serial monthly PSA 056 ng/mL 237 ng/mL 303 ng/mL demonstrated biochemical failure with significant uptake of 18 Ffluoroethylcholine in the abdominalpelvic lymph node on PET/CT images left and thus treatment with LHRH agonists was started Six months after the start of treatment PET/CT was negative right b A prostate cancer patient with increased PSA level 3680 ng/mL during hormone therapy Significant uptake of choline at the lumbar lymph nodes was demonstrated left The patient was treated with abiraterone acetate A PET/CT with 18 Ffluoroethylcholine right 3 months after the start of therapy showed a good metabolic response PSA 1297 ng/mLAccuracy is a frequent endpoint in diagnostic studies However a series of different outcomes should be addressed in PCa patient candidates for sLND For example the current literature shows that some patients benefit from sLND with approximately 9–19 remaining free from biochemical recurrence and approximately 26–34 remaining free from clinical recurrence 4 5 However these data indicate that the benefit of sLND in the majority of cases is prolonging survival and/or postponing hormone therapy but not achieving a complete cure Indeed whether these patients would have died from PCa without the removal of the lymph node metastases is unknown Information about the site of nodal relapse may be suboptimal particularly for sacral and retroperitoneal regions Extended retroperitoneal lymph node dissection is likely the only approach for limiting the effect of the Will Rogers phenomenon The risk of surgical complications is obviously also an ethical concern Although Pfister et al 1 reported no data about site/region accuracy for either 18 FFEC or 68GaPSMA PET/CT reports available in the literature indicate that the accuracy of radiolabeled choline for the detection of retroperitoneal lymph node recurrence ranges from 20 to 40 6 7 8 thus guiding the use of extended sLND in only a small percentage of patients
Keywords: