Reply by Authors

1
12. Presti, J. C., Jr., O’Dowd, G. J., Miller, M. C., Mattu, R. and Veltri, R. W.: Extended peripheral zone biopsy schemes in- crease cancer detection rates and minimize variance in pros- tate specific antigen and age related cancer rates: results of a community multi-practice study. J Urol, 169: 125, 2003 13. Prostate. In: AJCC Cancer Staging Manual, 6th ed. Edited by F. L. Greene, D. L. Page, I. D. Fleming, A. G. Fritz, C. M. Balch, D. G. Haller et al. New York: Springer-Verlag, part IX, chapt. 34, pp. 309 –316, 2002 14. Montironi, R., van der Kwast, T., Boccon-Gibod, L., Bono, A. V. and Boccon-Gibod, L.: Handling and pathology reporting of radical prostatectomy specimens. Eur Urol, 44: 626, 2003 15. Kundel, H. L. and Polansky, M.: Measurement of observer agreement. Radiology, 228: 303, 2003 16. Breeuwsma, A. J., Pruim, J., Jongen, M. M., Suurmeijer, A. J., Vaalburg, W., Nijman, R. J. et al: In vivo uptake of [11C]choline does not correlate with cell proliferation in human prostate cancer. Eur J Nucl Med Mol Imaging, 32: 668, 2005 17. Sutinen, E., Nurmi, M., Roivainen, A., Varpula, M., Tolvanen, T., Lehikoinen, P. et al: Kinetics of [11C]choline uptake in prostate cancer: a PET study. Eur J Nucl Med Mol Imaging, 31: 317, 2004 18. Bott, S. R., Young, M. P., Kellett, M. J., Parkinson, M. C. and Contributors to the UCL Hospitals’ Trust Radical Prosta- tectomy Database: Anterior prostate cancer: is it more dif- ficult to diagnose? BJU Int, 89: 886, 2002 EDITORIAL COMMENT Conventional 18 F-fluorodeoxyglucose-PET is known to have little use in newly diagnosed prostate cancer and there is substantial interest in alternative radiopharmaceutical markers. The authors have presented a promising investi- gation of 11 C-choline as such a marker, which combined the PET study with CT (which should improve anatomical local- ization), and included comparisons with TRUS and MRI. However, caution must be exercised in the interpretation of their data. Their patients had a relatively high risk profile. For example, mean PSA was 12.0 ng/ml compared to 7.8 ng/ml in a recent comparable series of 48 North American patients. 1 11 C-choline PET/CT only detected 1 of 23 tumor foci 5 mm or less in diameter. The clinical relevance of such small tumor foci in the prostate is questionable, but argu- ably the extension of the 11 C-choline PET/CT technique to nodal imaging (where most tumor deposits would be small) would likely be of limited sensitivity. Fergus Coakley Department of Radiology University of California, San Francisco San Francisco, California 1. Hom, J. J., Coakley, F. V., Simko, J. P., Qayyum, A., Lu, Y., Schmitt, L. et al: Prostate cancer: endorectal MR imaging and MR spectroscopic imaging— distinction of true-positive results from chance-detected lesions. Radiology, 238: 192, 2006 REPLY BY AUTHORS In patients with newly diagnosed prostate cancer knowl- edge of lymph node metastasis is of key importance for appropriate treatment planning but conventional imaging (CI) techniques have not been shown to have any role in this setting. 1 Although many nomograms have been de- veloped to quantify the risk of extraprostatic disease, 2 difficulties arise in the selection of the most appropriate nomogram with the optimal cutpoint for the single pa- tient. Pelvic lymph node dissection (PLND) remains the gold standard for N staging. Furthermore the clinical benefit and extent of PLND in patients with prostate cancer are still under discussion. Thus, new imaging ap- proaches would be welcome. 11 C-choline PET/CT has demonstrated good results for re-staging in patients with recurrent prostate cancer but little is known about its potential role for N staging. 3 We are now performing a prospective study to assess the accuracy of 11 C-choline PET/CT compared to CI before radical prostatectomy and extended PLND. Our prelimi- nary results show low sensitivity (approximately 65%) but high specificity and positive predictive value with this technique. The main drawback is the limited spatial res- olution of PET/CT scanners (approximately 4 to 5 mm) which hampers the recognition of micrometastasis. Fur- ther studies including an accurate cost-effectiveness anal- ysis are needed but PET/CT may be helpful in the decision to abort ineffective surgical treatment and to enhance specificity of CI. 1. Flanigan, R. C., McKay, R. C., Olson, M., Shankey, T. V., Pyle, J. and Waters, W. B.: Limited efficacy of preoperative com- puted tomographic scanning for the evaluation of lymph node metastasis in patients before radical prostatectomy. Urology, 48: 428, 1996 2. Briganti, A., Chun, F. K., Salonia, A., Zanni, G., Scattoni, V., Valiquette, L. et al: Validation of a nomogram predicting the probability of lymph node invasion among patients undergo- ing radical prostatectomy and an extended pelvic lymphad- enectomy. Eur Urol, 49: 1019, 2006 3. de Jong, I. J., Pruim, J., Elsinga, P. H., Vaalburg, W. and Mensink, H. J.: Preoperative staging of pelvic lymph nodes in prostate cancer by 11 C-choline PET. J Nucl Med, 44: 331, 2003 11 C-CHOLINE POSITRON EMISSION/COMPUTERIZED TOMOGRAPHY AND PROSTATE CANCER 960

Transcript of Reply by Authors

12. Presti, J. C., Jr., O’Dowd, G. J., Miller, M. C., Mattu, R. andVeltri, R. W.: Extended peripheral zone biopsy schemes in-crease cancer detection rates and minimize variance in pros-tate specific antigen and age related cancer rates: results of acommunity multi-practice study. J Urol, 169: 125, 2003

13. Prostate. In: AJCC Cancer Staging Manual, 6th ed. Edited byF. L. Greene, D. L. Page, I. D. Fleming, A. G. Fritz, C. M.Balch, D. G. Haller et al. New York: Springer-Verlag, partIX, chapt. 34, pp. 309–316, 2002

14. Montironi, R., van der Kwast, T., Boccon-Gibod, L., Bono, A. V.and Boccon-Gibod, L.: Handling and pathology reporting ofradical prostatectomy specimens. Eur Urol, 44: 626, 2003

15. Kundel, H. L. and Polansky, M.: Measurement of observeragreement. Radiology, 228: 303, 2003

16. Breeuwsma, A. J., Pruim, J., Jongen, M. M., Suurmeijer, A. J.,Vaalburg, W., Nijman, R. J. et al: In vivo uptake of[11C]choline does not correlate with cell proliferation inhuman prostate cancer. Eur J Nucl Med Mol Imaging, 32:668, 2005

17. Sutinen, E., Nurmi, M., Roivainen, A., Varpula, M., Tolvanen,T., Lehikoinen, P. et al: Kinetics of [11C]choline uptake inprostate cancer: a PET study. Eur J Nucl Med Mol Imaging,31: 317, 2004

18. Bott, S. R., Young, M. P., Kellett, M. J., Parkinson, M. C. andContributors to the UCL Hospitals’ Trust Radical Prosta-tectomy Database: Anterior prostate cancer: is it more dif-ficult to diagnose? BJU Int, 89: 886, 2002

EDITORIAL COMMENT

Conventional 18F-fluorodeoxyglucose-PET is known to havelittle use in newly diagnosed prostate cancer and there issubstantial interest in alternative radiopharmaceuticalmarkers. The authors have presented a promising investi-gation of 11C-choline as such a marker, which combined thePET study with CT (which should improve anatomical local-ization), and included comparisons with TRUS and MRI.However, caution must be exercised in the interpretation oftheir data. Their patients had a relatively high risk profile.For example, mean PSA was 12.0 ng/ml compared to 7.8ng/ml in a recent comparable series of 48 North Americanpatients.1 11C-choline PET/CT only detected 1 of 23 tumorfoci 5 mm or less in diameter. The clinical relevance of suchsmall tumor foci in the prostate is questionable, but argu-ably the extension of the 11C-choline PET/CT technique tonodal imaging (where most tumor deposits would be small)would likely be of limited sensitivity.

Fergus CoakleyDepartment of Radiology

University of California, San FranciscoSan Francisco, California

1. Hom, J. J., Coakley, F. V., Simko, J. P., Qayyum, A., Lu, Y.,Schmitt, L. et al: Prostate cancer: endorectal MR imagingand MR spectroscopic imaging—distinction of true-positiveresults from chance-detected lesions. Radiology, 238: 192,2006

REPLY BY AUTHORS

In patients with newly diagnosed prostate cancer knowl-edge of lymph node metastasis is of key importance forappropriate treatment planning but conventional imaging(CI) techniques have not been shown to have any role inthis setting.1 Although many nomograms have been de-veloped to quantify the risk of extraprostatic disease,2

difficulties arise in the selection of the most appropriatenomogram with the optimal cutpoint for the single pa-tient. Pelvic lymph node dissection (PLND) remains thegold standard for N staging. Furthermore the clinicalbenefit and extent of PLND in patients with prostatecancer are still under discussion. Thus, new imaging ap-proaches would be welcome.

11C-choline PET/CT has demonstrated good results forre-staging in patients with recurrent prostate cancer butlittle is known about its potential role for N staging.3 Weare now performing a prospective study to assess theaccuracy of 11C-choline PET/CT compared to CI beforeradical prostatectomy and extended PLND. Our prelimi-nary results show low sensitivity (approximately 65%) buthigh specificity and positive predictive value with thistechnique. The main drawback is the limited spatial res-olution of PET/CT scanners (approximately 4 to 5 mm)which hampers the recognition of micrometastasis. Fur-ther studies including an accurate cost-effectiveness anal-ysis are needed but PET/CT may be helpful in the decisionto abort ineffective surgical treatment and to enhancespecificity of CI.

1. Flanigan, R. C., McKay, R. C., Olson, M., Shankey, T. V., Pyle,J. and Waters, W. B.: Limited efficacy of preoperative com-puted tomographic scanning for the evaluation of lymphnode metastasis in patients before radical prostatectomy.Urology, 48: 428, 1996

2. Briganti, A., Chun, F. K., Salonia, A., Zanni, G., Scattoni, V.,Valiquette, L. et al: Validation of a nomogram predicting theprobability of lymph node invasion among patients undergo-ing radical prostatectomy and an extended pelvic lymphad-enectomy. Eur Urol, 49: 1019, 2006

3. de Jong, I. J., Pruim, J., Elsinga, P. H., Vaalburg, W. andMensink, H. J.: Preoperative staging of pelvic lymph nodesin prostate cancer by 11C-choline PET. J Nucl Med, 44: 331,2003

11C-CHOLINE POSITRON EMISSION/COMPUTERIZED TOMOGRAPHY AND PROSTATE CANCER960