Detection of recurrent prostate cancer with 18F-fluorocholine PET/CT in relation to PSA level at the time of imaging
Sandi A. Kwee
0
1
Marc N. Coel
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1
John Lim
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1
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S. A. Kwee Department of Medicine, John A. Burns School of Medicine, University of Hawaii at Manoa
, Honolulu,
HI, USA
1
S. A. Kwee (&) M. N. Coel J. Lim Hamamatsu/Queen's PET Imaging Center, The Queen's Medical Center
, 1301 Punchbowl St., Honolulu,
HI 96813, USA
Purpose To evaluate fluorine-18 fluorocholine (FCH) PET/CT for the detection of recurrent prostate cancer in relation to prostate-specific antigen (PSA) level. Methods FCH PET/CT was performed in 50 patients with rising PSA levels at follow-up of primary treatment of prostate cancer (radical prostatectomy in 28, radiation therapy in 13, and brachytherapy in 9). PET detection rates were determined at various PSA thresholds and examined by receiver operating characteristic analysis. Results Findings consistent with recurrent prostate cancer were noted on FCH PET/CT in 31/50 (62 %) patients, with positive findings in 17/18 (94 %), and 11/13 (85 %), 2/7 (29 %), and 1/12 (8 %) patients with PSA [4, [2-4, [0.5-2, and B0.5 ng/mL, respectively. These findings were indicative of local/regional recurrence in 23 cases and systemic recurrence in 8 cases, with only a single route of recurrence (i.e., either hematogenous, lymphatic, or intraprostatic) in 84 % of PET scans with positive findings. Abnormal tumor activity was detected in 88 % of patients with a PSA level of 1.1 ng/mL or higher, and in only 6 % of patients with a PSA level below this threshold value. Conclusion FCH PET/CT may serve to identify the route of tumor progression in patients with recurrent prostate cancer; however, the likelihood of tumor detection may be related to the PSA level at the time of imaging.
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A rising serum prostate-specific antigen (PSA) level is
often the first indicator of recurrent disease in patients with
prostate cancer treated with radiation therapy (RT) or
radical prostatectomy (RP). At 5 years following such
primary treatments, rising PSA levels can be detected in
approximately 1520 % of low-risk patients, and
approximately 50 % of high-risk (i.e., Gleason score 810, PSA
[20 ng/mL, stage T3) patients [1, 2]. Localizing recurrent
tumors in these patients has proven to be a significant
challenge when using conventional diagnostic imaging,
particularly when the PSA level has not yet risen
substantially [35]. While recurrence patterns in prostate
cancer are known to vary by treatment [6, 7], awareness of
these patterns is not sufficient to support the customization
of salvage therapy for recurrent prostate cancer.
Patientindividualized treatment approaches for recurrent prostate
cancer could be enhanced if tumor spread along local,
lymphatic, and hematogenous routes are correctly
identified shortly after a rise in PSA is detected.
PET imaging using tracer analogs of choline has shown
significant promise for detecting prostate cancer [813].
The rationale for using choline derivatives as oncologic
PET tracers is based on the observation that choline
transport and phosphorylation are upregulated in most
cancers, including prostate cancer [1417]. While there are
some data on the performance of choline-based PET
imaging for whole-body staging of prostate cancer, some
uncertainty remains as to its diagnostic sensitivity in
patients with low levels of PSA following RP, external
beam RT, and interstitial brachytherapy. The purpose of
this study is to evaluate the detection rate of FCH PET/CT
in patients with rising PSA levels following primary
treatment of prostate cancer, paying particular attention to
the routes of tumor progression that can be identified as
well as the potential relationship between PSA level and
tumor detection.
Fifty sequential patients with a history of clinically
localized prostate cancer who were noted to have an elevated
PSA level [0.2 ng/mL on at least two serial measurements
after completion of RP, RT, or interstitial brachytherapy
were recruited to undergo FCH PET/CT imaging in this
institutional review board-approved clinical research study.
All patients gave written informed consent before their
participation. Hormone-nave patients as well as patients
who received luteinizing hormone-releasing hormone
(LHRH) agonist therapy for at least 3 months prior to the
detection of an elevated PSA, including those treated with
an LHRH agonist in conjunction with primary treatment,
were eligible for this study. However, patients in whom
LHRH agonist therapy was started recently, namely within
3 months, or following the detection of an elevated PSA
level were excluded from the study.
Radiopharmaceutical synthesis and PET imaging
FCH synthesis was performed by fluorination of
ditosylmethane with fluorine-18 followed by alkylation of the
fluorotosylmethane intermediate with dimethylethanolamine
using a chemical process control unit (CTI/Siemens CPCU,
CTI/Siemens, Knoxville, TN) [18]. All synthesis products
passed standard assays for radiochemical purity, radionuclidic
identity, chemical purity, and pyrogeni (...truncated)