OBJECTIVE: This study evaluated the usefulness of 18F-fluorocholine PET/CT in restaging patients with a history of prostate adenocarcinoma who faced biochemical relapse after early radical treatment, and correlated the technique's disease detection rate with a set of variables and clinical and pathological parameters.
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MATERIAL AND METHODS: This was a retrospective multicentre study which included 374 patients referred for choline PET/CT who had biochemical relapse. In the end, 233 patients who met the following inclusion criteria were analysed: diagnosis of prostate cancer; early radical treatment; biochemical relapse; main clinical and pathological variables; and clinical, pathological and imaging data needed to validate the results. Criteria used to validate the PET/CT: findings from other imaging techniques, clinical follow-up, treatment response and histological analysis. Different statistical tests were used depending on the distribution of the data to correlate the results of the choline PET/CT with qualitative (T, N, early prostatectomy vs. other treatments, hormone therapy concomitant to choline PET/CT) and quantitative (age, Gleason score, PSA levels at diagnosis, PSA nadir, PSA on the day of the choline PET/CT or trigger PSA and PSADT) variables. We analysed whether there were independent predictive factors associated with the positive PET/CT result. All statistical tests were considered two-sided and significant values where p< 0.05.
RESULTS: The choline PET/CT was positive in 111 of 233 patients (detection rate: 47.6%) and negative in 122 (52.4%). Disease locations: prostate or prostate bed in 26 patients (23.4%); regional and/or distant lymph nodes in 52 (46.8%); and metastatic bone disease in 33 (29.7%). Positive findings were validated by: results from other imaging techniques in 35 patients (15.0%); at least 6 months of clinical follow-up in 136 (58.4%); treatment response in 24 (10.3%); histological analysis of lesions in 17 (7.3%); and follow-up plus imaging results in 21 (9.0%). The statistical analysis of qualitative variables, corresponding to patients' clinical characteristics, and the positive/negative final PET/CT results revealed that only whether or not early treatment with radical prostatectomy was done was statistically significant (p< 0.001), with the number of positive results higher in patients who did not undergo a radical prostatectomy. Among the quantitative variables, Gleason score, trigger PSA and PSADT clearly differentiated the two patient groups (positive and negative choline PET/CT): p=0.010, p=0.001 and p=0.025, respectively. A Gleason score of < 5 or ≥8 clearly differentiated positive from negative PET. Trigger PSA: mean of 8 ngr/ml for positive PET/CT vs. 2.8 for negative PET/CT; PSADT: mean of 8 months for positive PSADT and 12.6 for negative PSADT. The optimal cut-off points were: 3 ngr/ml for trigger PSA and 6 months for PSADT (Youden index/ROC curve). Analysing these two variables together showed that PSADT was more conclusive in patients with lower PSA Trigger. Analysing variables by location showed that only PSADT was able to differentiate between those with disease confined to the prostate compared with the other two locations (lymph nodes and bone), with shorter PSADT in these two, which was statistically significant (p< 0.002). In the patient group with PSA of < 1.5 ngr/ml, 30.8% had the disease, 7% of whom had metastatic bone disease. In the multivariate logistic regression, the risks factors that were clearly independent for those with positive PET/CT were: PSA >3 ngr/ml; no early prostatectomy; and Gleason score of ≥8.
CONCLUSION: Our results support the usefulness of 18F-fluorocholine PET/CT in biochemical relapse of prostate cancer after radical treatment, with an overall disease detection rate close to 50%, and it can be recommended as first-line treatment. As mentioned above, besides PSA levels on the day of the PET/CT, there are other clinical and pathological variables to consider in order to screen patients properly and thus minimise the number of nodular lesions and increase the diagnostic accuracy of the exam.
Rodado-Marina S1, Coronado-Poggio M, García-Vicente AM, García-Garzón JR, Alonso-Farto JC, de la Jara AC, Maldonado-Suárez A, Rodríguez-Fernández A Are you the author?
Department of Nuclear Medicine, La Paz Universitary Hospital, Madrid, Spain; Department of Nuclear Medicine, Universitary Hospital, Ciudad Real, Spain; CETIR Unitat PET Esplugues, Barcelona, Spain; Gregorio Marañón Universitary Hospital, Madrid, Spain; Department of Nuclear Medicine, Quirón Hospital, Torrevieja, Spain; Quirón Universitary Hospital, Madrid, Spain; Department of Nuclear Medicine, Virgen de las Nieves Universitary Hospital, Granada, Spain.
Reference: BJU Int. 2015 Jun;115(6):874-83