Genitourinary Cancer

PV QA 1 - Poster Viewing Q&A 1

SU_27_2276 - Evaluating Patterns of Prostate Cancer Recurrence on 18F-DCFBC PET/CT Imaging in Relationship to RTOG Consensus Post-prostatectomy and Pelvic Lymph Node Treatment Volumes

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

Evaluating Patterns of Prostate Cancer Recurrence on 18F-DCFBC PET/CT Imaging in Relationship to RTOG Consensus Post-prostatectomy and Pelvic Lymph Node Treatment Volumes
A. R. Horn1, C. P. Smith2, S. Harmon3, H. Ning4, M. G. Pomper5, E. E. Schott6, T. Cooley-Zgela7, P. Choyke8, E. Mena Gonzalez9, B. Turkbey8, D. E. Citrin4, L. Lindenberg9, and L. Rowe4; 1Walter Reed National Military Medical Center, Bethesda, MD, 2Department of Radiation Medicine, Georgetown University Hospital, Washington, DC, 3Leidos Biomedical Research, Inc., National Cancer Institute, NIH, Frederick, MD, 4Radiation Oncology Branch, National Cancer Institute, NIH, Bethesda, MD, 5Department of Radiology, Johns Hopkins University, Baltimore, MD, 6Radiation Oncology Branch, National Cancer Institute, Bethesda, MD, 7National Cancer Institute, Bethesda, MD, 8Molecular Imaging Program, National Cancer Institute, NIH, Bethesda, MD, 9Molecular Imaging Program, National Cancer Institute, Bethesda, MD

Purpose/Objective(s): Standard imaging is inadequate at identifying recurrent disease post-operatively after prostate cancer biochemical failure. Prostate cancer selectively expresses prostate specific membrane antigen (PSMA). 18F-DCFBC is a novel radiolabeled PET agent that binds PSMA and provides new information regarding PSMA expression and localization of recurrent disease. We identified 18F-DCFBC PET avid lesions after biochemical failure and compared these to consensus Radiation Therapy Oncology Group (RTOG) volumes for prostate fossa and pelvic lymph nodes (LN).

Materials/Methods: 49 patients enrolled on a prospective IRB approved clinical trial. Each presented with biochemical recurrence post-prostatectomy, PSA of ≥0.2ng/ml, and no site of recurrence on standard imaging. All patients underwent whole body 18F-DCFBC PET/CT. RTOG consensus prostate fossa clinical target volume (PF-CTV) contours and pelvic LN volumes (LN-CTV) were drawn by 2 radiation oncologists. PF-CTV limited the superior boarder to 2cm above the pubic symphysis, while the expanded prostate fossa (EPF-CTV) limited the border to 4 cm. 18F-DCFBC avid lesions were contoured by a radiologist on the corresponding CT while blinded to consensus contours. PET images were fused to CT, and 18F-DCFBC avid areas were compared with consensus contours.

Results: Forty-two 18F-DCFBC avid lesions were identified in 26 patients. 40.5% (17/42) of lesions were encompassed within PF-CTV. No lesions were seen within the EPF-CTV. 16.7% (7/42) of lesions were encompassed by LN-CTV. 4.8% (2/42) of recurrent lesions in the pelvis were not within RTOG contours. One lesion was peri-urethral at the level of the penile bulb, while another was identified adjacent to the posterior-lateral rectal wall. 38.1% (16/42) of lesions were classified as distant metastatic disease. Of the 26 patients, 50% (13/26) had recurrent disease within PF-CTV only. 15.4% (4/26) patients had recurrent disease outside of PF-CTV but within LN-CTV. 27.0% (7/26) patients were found to have distant metastatic disease. 7.7% (2/26) patients had local recurrence in areas that were not encompassed by PF-CTV and LN-CTV.

Conclusion: Advanced imaging may identify areas of recurrence, inform target volumes, and select appropriate patients for systemic therapy after biochemical failure in prostate cancer. Half of patients had recurrent disease encompassed by consensus radiation volumes for prostate fossa, with only a small number of patients with local disease identified outside this volume. In 15.4% of patients, inclusion of all identified disease would require regional nodal irradiation for adequate coverage. Importantly, 27% of patients had occult metastatic disease and would not have been salvaged.

Author Disclosure: A.R. Horn: Stock Options; ACCURAY. C.P. Smith: None. S. Harmon: NIH Contract; National Institutes of Health. H. Ning: None. M.G. Pomper: Research Grant; National Institutes of Health. Director of Nuclear Medicine; Johns Hopkins University. E.E. Schott: None. T. Cooley-Zgela: None. E. Mena Gonzalez: None. D.E. Citrin: Employee; US Army. Research Grant; National Institutes of Health. L. Lindenberg: None.

Send Email for Adam Horn


Assets

SU_27_2276 - Evaluating Patterns of Prostate Cancer Recurrence on 18F-DCFBC PET/CT Imaging in Relationship to RTOG Consensus Post-prostatectomy and Pelvic Lymph Node Treatment Volumes



Attendees who have favorited this

Please enter your access key

The asset you are trying to access is locked. Please enter your access key to unlock.

Send Email for Evaluating Patterns of Prostate Cancer Recurrence on 18F-DCFBC PET/CT Imaging in Relationship to RTOG Consensus Post-prostatectomy and Pelvic Lymph Node Treatment Volumes