11C Choline- PET in prostate RT
Influence of 11C-choline PET/CT on the treatment planning for salvage radiation therapy in patients with biochemical recurrence of prostate cancer

https://doi.org/10.1016/j.radonc.2011.05.005Get rights and content

Abstract

Background and purpose

The present study evaluates the incidence of 11C-choline PET/CT positive findings in patients with recurrent prostate cancer referred for salvage radiotherapy (SRT) and the influence on the definition of the planning target volume (PTV).

Material and methods

Thirty-seven patients treated with radical prostatectomy and referred to SRT to the prostatic fossa because of biochemical relapse, were analysed retrospectively. All patients underwent 11C-choline PET/CT before radiotherapy. The influence of PET/CT on the extent of the PTV was analysed. The median total follow up after SRT was 51.2 months.

Results

11/37 (30%) patients had a positive finding in the 11C-choline PET/CT, 5 (13%) outside of the prostatic fossa (iliac lymph nodes), implicating an extension of the PTV. Patients with positive 11C-choline PET/CT had a significant higher PSA value than patients with no pathologic uptake (p = 0.03). Overall, at the end of follow up 56% of the patients had a PSA  0.2 ng/ml and 44% had a biochemical relapse of prostate cancer.

Conclusions

11C-choline PET/CT detects abnormalities outside of the prostatic fossa in 13% of patients referred for SRT because of biochemical relapse after radical prostatectomy, affecting the extent of the PTV. Prospective studies need to be implemented to evaluate the benefit of SRT with a PTV based on 11C-choline PET/CT.

Section snippets

Patients

Thirty-seven consecutive asymptomatic patients (mean age: 63.6 ± 6.2 yr, range: 49–78), all treated primarily with radical prostatectomy for prostate cancer, referred for salvage radiation therapy because of biochemical evidence of recurrence, were retrospectively included in this study. They underwent a 11C-choline-PET/CT scan prior to radiotherapy. The period of inclusion was from January 2005 to December 2006. Inclusion criterion to perform a 11C-choline-PET/CT scan was biochemical evidence of

Results

Characteristics, imaging results and outcome of the patients are summarized in Table 2. The median time for evaluation of initial PSA response after radiotherapy was 1.7 months. The median total follow up after radiotherapy was 51.2 months (Table 1).

Discussion

Our results demonstrate an extension of the planning target volume in a considerable percentage (13%) of prostate cancer patients referred for prostatic fossa SRT because of biochemical recurrence after prostatectomy, if a 11C-choline PET/CT scan is used in the treatment planning. In particular 4/5 patients with lymph node uptake had negative surgical margins, a feature which in some studies is associated with an unfavourable response rate to prostatic fossa SRT, as the PTV, probably does not

Conclusion

11C-choline PET/CT scan leads to an extension in the planning target volume in 13% of cases, when performed in a group of patients referred for radiation therapy because of biochemical recurrence after radical prostatectomy. 75% of patients with extended PTV according to the 11C-choline PET/CT scan returned findings, were relapse free in the follow up period. Therefore, PET/CT might be useful to individualize treatment in those patients, however further prospective studies are needed to assess

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