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Journal of Clinical Oncology, Vol 22, No 2 (January 15), 2004: pp. 380-381 © 2004 American Society of Clinical Oncology. DOI: 10.1200/JCO.2004.99.224
In Reply:University of Cincinnati, Cinncinatti, OH, University of Texas Health Science Center at San Antonio, San Antonio, TX, University of Michigan, Ann Arbor, MI, M.D. Anderson Cancer Center, Houston, TX, The Johns Hopkins University School of Medicine, Baltimore, MD We read with interest the comments of Drs Sodee, Faulhaber, Nelson, and Bakale concerning our report [1]. The authors question the validity of our conclusions by 1) submitting that the imaging technology we used did not adhere to the state of clinical science in image acquisition and processing, and 2) suggesting that registration of indium-111–capromab pendetide radioimmunoscintigraphy and computed tomography would have unequivocally delineated the location of uptake in pelvic and abdominal lymph nodes. Our study tested the reliability and generalizability of published results reporting indium-111–capromab pendetide radioimmunoscintigraphy as a prognostic test for a durable response to salvage radiation therapy after failed radical prostatectomy [2,3]. We carefully followed the cohorts and linked quality imaging studies from a major medical center to clinical outcome. Our database was compiled with precision and verified for quality assurance with the resources of the University of Michigan General Clinical Research Center and the Specialized Program of Research Excellence in Prostate Cancer (Ann Arbor, MI). Analysis of the data was performed by researchers in radiation oncology, urology, nuclear medicine, and biostatistics. The thoroughness of the data collection and the accuracy of the conclusions were specifically noted by qualified researchers who are among the reviewers for the Journal of Clinical Oncology. We respectfully disagree that our study was "cursory." Concerning the technical matter of single photon emission computed tomography acquisition modes, previous reports about the indium monoclonal antibody (In-mab) scan describe data acquisition in both 64 x 64 and 128 x 128 matrices [2,4,5]. In reference to the use of a 64 x 64 versus a 128 x 128 computer acquisition matrix, Sodee et al [5] reported in a review of 2,154 patients that although the larger 128 x 128 matrix facilitated reading images, no significant difference in accuracy between the two acquisition modes was evident. Paradoxically, Sodee et al supported this conclusion with a reference to an abstract in which results described the 128 x 128 acquisition matrix as much more sensitive than the 64 x 64 acquisition matrix [6]. The fact remains that with a similar imaging technique and acquisition technology as that used in previous reports [2,3,7], we found it was not possible to demonstrate that men with a negative scan outside the prostate bed were any more likely to have a durable response to salvage radiation therapy than those with a positive scan. To date, no peer-reviewed publication has reproduced the results of previous reports. Technology evolves. A well-characterized retrospective cohort study will never match continuous refinements in technology. To expect so is an unreasoned premise to challenge the validity of an investigation. There is no adequate reference standard for indium-111–capromab pendetide radioimmunoscintigraphy. Therefore, the best test of In-mab scan accuracy is assiduous clinical follow-up to improve the classification of In-mab scan findings [8]. The prostate-specific antigen (PSA) level is a debated end point in the evaluation of new treatment methods or modalities [9-11]. Large multicenter and prospective analyses are needed to test whether PSA control after salvage radiation therapy leads to prolonged prostate cancer specific survival. Nevertheless, a favorable PSA profile after salvage radiation therapy is currently the best short-term surrogate for post- treatment prostate cancer survival and in turn success of salvage radiation therapy. Regarding the advocacy of image fusion, registering the In-mab scan to the negative computed tomography scan for each cohort may or may not change the results. Midline abdominal positivity by In-mab imaging may demonstrate mesenteric lymph nodes, but image registration likely will not compensate for normal physiological bowel movement. Image registration is an established and valuable imaging tool. It is not unequivocal and requires its own careful assessment [12,13]. We noted a recent press release entitled "Cytogen, Siemens and University Hospitals of Cleveland Join Forces to Promote Breakthroughs in Prostate Cancer Imaging" (http://www.cytogen.com/pr/nr_06_23_03.html), in which Dr Sodee describes his technique. It is possible that his technique will improve image results. We wish him success in his efforts and look forward to peer-reviewed publication of his work. Our investigation did not test the use of capromab pendetide imaging for radiation therapy treatment planning or prostate cancer staging. There was never an assertion that future applications with advanced versions of capromab penditide have no value. However, for postprostatectomy PSA relapse, indium-111–capromab pendetide imaging results were not prognostic of postsalvage radiation therapy PSA outcome. The results are relevant for the imaging method used and stand on their own merit. Authors' Disclosures of Potential Conflicts of Interest The following authors or their immediate family members have indicated a financial interest. No conflict exists for drugs or devices used in a study if they are not being evaluated as part of the investigation. Owns stock (not including shares held through a public mutual fund): Richard L. Wahl, CT Molecular Imaging. Acted as a consultant within the last 2 years: Richard L. Wahl, Berlex, Millenium N Hon, Corixa. Performed contract work within the last 2 years: Richard L. Wahl, General Electric Medical Systems. Received more than $2,000 a year from a company for either of the last 2 years: Richard L. Wahl, General Electric Medical Systems, Cardinal Health, GlaxoSmithKline. REFERENCES
1. Thomas CT, Bradshaw PT, Pollock BH, et al: Indium-111-capromab pendetide radioimmunoscintigraphy and prognosis for durable biochemical response to salvage radiation therapy in men after failed prostatectomy. J Clin Oncol 21:1715-1721, 2003
2. Kahn D, Williams RD, Haseman MK, et al: Radioimmunoscintigraphy with In-111-labeled capromab pendetide predicts prostate cancer response to salvage radiotherapy after failed radical prostatectomy. J Clin Oncol 16:284-289, 1998 3. Levesque PE, Nieh PT, Zinman LN, et al: Radiolabeled monoclonal antibody indium 111-labeled CYT-356 localizes extraprostatic recurrent carcinoma after prostatectomy. Urology 51:978-84, 1998[CrossRef][Medline] 4. Kahn D, Williams RD, Seldin DW, et al: Radioimmunoscintigraphy with 111indium labeled CYT-356 for the detection of occult prostate cancer recurrence. J Urol 152:1490-1495, 1994[Medline] 5. Sodee DB, Malguria N, Faulhaber P, et al: Multicenter ProstaScint imaging findings in 2154 patients with prostate cancer. The ProstaScint Imaging Centers. Urology 56:988-93, 2000[CrossRef][Medline] 6. Sodee DB, Malguria N, Nelson AD, et al: Optimization of ProstatScint sensitivity in the diagnosis and staging of prostate cancer. J Nucl Med 41:116P, 2000 (abstr 456) 7. Kahn D, Austin JC, Miller S, et al: In-111 capromab pendetide mab scan predicts response to radiotherapy to the prostate fossa in men with tumor recurrence following radical prostatectomy. J Urol 161:239, 1999 (abstr 919; suppl 4)
8. Hillman BJ: Noninterpretive skills for radiology residents. Critical thinking: Deciding whether to incorporate the recommendations of radiology publications and presentations into practice. AJR Am J Roentgenol 174:943-946, 2000 9. Kagan AR, Schulz RJ: A commentary on dose escalation and bNED in prostate cancer. Int J Radiat Oncol Biol Phys 55:1151-1152, 2003[Medline] 10. Kupelian PA, Katcher J, Levin HS, et al: Stage T1-2 prostate cancer: A multivariate analysis of factors affecting biochemical and clinical failures after radical prostatectomy. Int J Radiat Oncol Biol Phys 37:1043-1052, 1997[CrossRef][Medline] 11. Pollack A, Zagars GK, Antolak JA, et al: In Response to Drs. Kagan and Schulz. Int J Radiat Oncol Biol Phys 55:1151-1152, 2003 12. Thomas CT, Meyer CR, Koeppe RA, et al: A Positron-emitting internal marker for identification of normal tissues by PET: Phantom studies and validation in patients. Molecular Imaging and Biology 5:79-85, 2003
13. Osman MM, Cohade C, Nakamoto Y, et al: Clinically significant inaccurate localization of lesions with PET/CT: Frequency in 300 patients. J Nucl Med 44:240-243, 2003
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Copyright © 2004 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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