MOLECULAR IMAGING NEWS
Phoenix Molecular Imaging
Carbon-11 Acetate PET/CT Imaging
for Prostate Cancer
The treatment landscape for prostate cancer has been revolutionized by the arrival of multiple novel treatment
approaches and agents over the last few years. After initial treatment with surgery or radiation however, up to
40% of patients will experience PSA relapse. Knowing the location of a cancer recurrence is important since
recurrence in the prostate bed or pelvic lymph nodes may be amenable to additional focal therapy. Finding lesions outside of the pelvis (distant metastases) may require systemic treatment with hormones combined with
radiation or other focal treatment.
The primary difficulty in this situation is that standard imaging techniques such as technetium bone scan, CT
scans and MRI are usually unable to see small recurrent tumors or metastases. On the other hand, PET scans
that work by exploiting various aspects of cancer metabolism, can often visualize and locate these small tumors.
Carbon-11 (C11) Acetate PET/CT is an imaging technique that has been shown to be very useful in patients
with prostate cancer. In prostate cancer, there is an increase in fatty acid metabolism which is due, in part, to the
up-regulation of intracellular fatty acid synthase. C11-Acetate is able to visualize this metabolic process and can
thereby detect and localize recurrent prostate cancer and prostate cancer metastases. Lymph node lesions as
small as 4-5 mm can be identified by this technique.
Phoenix Molecular Imaging and C11-Acetate
A open access clinical trial study evaluating C11 Acetate PET/CT has been conducted by Phoenix Molecular
Imaging under the direction of Fabio Almeida MD. In this study, over 1000 patients with recurrent prostate cancer (as evidenced by a rising PSA) have been studied using a high resolution PET/CT camera. The study has
demonstrated an overall detection rate of 88%. The PSA level is being shown to have an influence on the detection rate. When the PSA is > 1.0 ng/mL the detection rate is 90%. With a PSA of 0.2 - 1.0 ng/mL the detection rate is 74%. The doubling time (or rate of PSA rise) also appears to have an influence, such that when the
PSA is <1.0 and the doubling time is < 3 months, the detection rate is increased to 90%.
In This Issue
PET/CT Camera at Phoenix Molecular Imaging
Intro to C11-Acetate
Guided Treatment &
Case Example 2
Mr. S is 69 years old and was diagnosed with PCa in 2010.
His Gleason score was 8 (4+4) and his PSA was 4.8ng/mL. He
underwent a prostatectomy at which time extracapsular extension was found.
After surgery his PSA was initially undetectable, but it began to
rise a few months later and within a year his PSA had risen to
0.5 ng/mL, with a doubling rate of 3.18 months.
C11-Acetate uptake in the prostate bed
Case Example 1
Mr, V is 76 years old and was diagnosed with Prostate
Adenocarcinoma (PCa) in 2000. His Gleason score was 8
(4+4) and his PSA was 4.0. He underwent a prostatectomy in
2001 and his PSA remained <0.1 for several years.
His PSA then began to rise and by 2011 his PSA was 3.3 ng/
mL and doubling at a rate of 10.9 months.
A C11-Acetate PET/CT imaging study was performed which
showed a small recurrence of the cancer in the prostate bed
(yellow arrow on image above). No involved lymph nodes
were detected and no lesions were seen on the C11 study to
suggest distant metastatic disease.
Based on the results of the C11-Acetate imaging study, Mr. V
proceeded with Intensity Modulated Radiation Therapy
(IMRT) to the prostate bed. The radiation therapy plan was
modified from the typical “blind” application of radiation to this
region. Instead, the area of recurrent cancer identified on the
imaging study was centered on by the radiation and less
radiation was then given to the surrounding areas, including
the urinary bladder and rectum.
Mr. S’s urologist told him it was most likely that the cancer had
metastasized, and probably involved the bone given how quickly his PSA was rising. A technetium bone scan was performed,
which was negative for bone metastasis. Even so, he was advised to begin hormone therapy as his best option.
Mr. S was not ready to start hormone therapy based on the
A C11-Acetate PET/CT imaging study was performed which
showed a small focus of increased metabolism in the right seminal vesicle bed (yellow arrow on image below). This indicated
locally residual cancer left behind after surgery which was now
growing. There were no involved lymph nodes on the scan and
no lesions were seen on the C11 study to suggest distant metastatic disease to the bone or elsewhere.
Based on the C11-Acetate imaging study, Mr. S underwent
IMRT. The radiation therapy was performed to the entire prostate bed region but also with a radiation “boost” to the area of
cancer noted on the imaging study.
How has he done?
After his radiation treatment, his PSA fell to <0.1 ng/mL and
has remained stable at that level for 3 years so far. He experienced no side effects from the radiation treatment and has not
yet had to start any hormone therapy.
How has he done?
After his radiation treatment, the PSA fell to <0.1 ng/mL and
has remained stable at that level for 4 years. He experienced
no side effects from the radiation treatment and no other
treatment has thus far been necessary. He is happy that he
has not yet needed to start hormone therapy.
C11-Acetate focus in the right seminal vesicle bed
The overall detection rate
for cancer recurrence or
metastatic disease with
C11-Acetate is 88%
which compares to 74%
for C11-Choline - as reported by Mitchell et.al [J
Urol 189(4): 1308-1313].
Lesion detect at lower
PSA levels (<1.0ng/mL)
are of particular clinical
interest, as it is at this
range where many treatment decisions are made,
such as otherwise “blind”
radiation to the prostate
bed or the initiation of
hormone therapy. C11–
or F18 Choline performance in this range is
poor, with a detection
rate of only 44%. This
compares to a much
higher detection rate of
74% for C11-Acetate.
Additionally, when performed in the context of a
low doubling time (<3
months), the detection
rate for C11-Acetate in
this low PSA range is
C11-Acetate can be useful to assist with treatment decisions by providing targets for focal salvage treatment, adding
treatment options at least
40% of the time.
C11-Acetate uptake in a right peri-rectal lymph node
Case Example 3
Mr, W is 72 years old and was diagnosed with PCa in 2006. His Gleason score
was 9 (5+4) and his PSA was 10.8. He underwent a prostatectomy and his PSA
remained <0.1 for 7 years.
His PSA then began to rise, and by 2013 it was 0.63 ng/mL with a doubling rate of
9.3 months. An abdominal and pelvic CT scan as well as technetium bone scan
A C11-Acetate PET/CT imaging study was performed which showed a small metabolic 9 mm lymph node to the right of and next to the rectum (yellow arrow on image
above). No metabolic lesions were seen in the prostate bed and no lesions were
seen on the C11 study to suggest distant metastatic disease.
Radiation treatment to the prostate bed with radiation extending to the pelvic lymph
nodes is technically viable. His case was complicated, however, by a history of ulcerative colitis, making standard radiation problematic. He opted to undergo Intensity
Modulated Proton Therapy. The proton therapy was administered to the pelvic lymph
nodes detected on the C11-Acetate imaging alone. The C11-Acetate images were
electronically integrated into the treatment plan to help guide the proton therapy.
How has he done?
His PSA decreased to <0.1 ng/mL and has remained at that level for 20 months so
far after his proton radiation treatment,. He experienced no side effects from the radiation treatment and has not had any exacerbation of his ulcerative colitis. He will
continue to follow his PSA.
Case Example 4
Mr. SE is 74 years old and was diagnosed with PCa in 2003. His Gleason score
was 6 (3+3) and his PSA was 10.4 ng/mL. He underwent a high dose brachytherapy to the prostate (HDR). In 2008 his PSA began to rise and a Combidex study
showed involvement of left pelvic lymph nodes. He had IMRT radiation to the lymph
nodes but his PSA did not respond. He was treated with Cytoxan, Luekine, and Metformin. His PSA continued to rise. A CT scan in 2013 showed no evidence of metastatic disease. By 2015 his PSA had risen to 7.46 ng/mL with a doubling rate of 7.9
A C11-Acetate PET/CT imaging study
was performed which showed diffusely
increased metabolism in the bone associated with innumerable tiny areas of
scarring/sclerosis (yellow arrows on
image to the right). This was indicative
of diffuse bone metastasis.
Based on the C11-Acetate imaging
study, Mr. SE underwent a bone biopsy
which confirmed the presence of bone
metastasis. He was started on systemic
treatment with hormone therapy.
Give us a call for more
information about C11Acetate PET/CT Imaging
4540 E. Cotton Gin Loop
Phoenix, AZ 85040
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C11-Acetate uptake in the bones
C11 Acetate guided Treatment & Response
In our study, salvage radiation treatment to the lesions identified by C11-Acetate
was performed either alone or conjunction with hormone therapy in a large number
of patients (40%). Follow up of these patients to assess the duration of PSA response is ongoing. Thus far, in those treated with radiation treatment alone, 50%
have shown a persistent drop in PSA for at east 1 year. In those patients for which
greater than 3 years of follow up is available, 29% continue to have a durable PSA
response to treatment and have not yet required additional treatment. These results
are very encouraging. An even larger number of durable PSA responses will be
expected in those who receive C11 Acetate guided radiation treatment and also at
least a short course of hormone therapy.
C11-Acetate PET/CT imaging appears highly useful in men with recurrent prostate cancer. It has a high detection rate even at low PSA levels, and in many cases
identifies areas of recurrent or regionally metastatic disease that can be treated with
radiation or other focal therapy. Treatment with hormone therapy may be avoided or
significantly delayed. In other cases, C11-Acetate may show evidence of distant
metastatic disease not seen by other techniques, thereby helping to better identify
situations where systemic/hormone therapy is the most appropriate course of action.