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Analysis of intraprostatic therapeutic effects in prostate cancer patients using [(11)C]-choline pet/ct after external-beam radiation therapy.

By:
Contributors: Melinda Wuest, PhD, Matthew Parliament, MD, FRCPC, Nawaid Usmani, MD, FRCPC
Curr Oncol. 2013 Apr;20(2):104-10. doi: 10.3747/co.20.1217.

Abstract

PURPOSE:

The objective of the present study was to analyze, with relatively high sensitivity and specificity, uptake properties of [(11)C]-choline in prostate cancer patients by means of positron-emission tomography (pet)/computed tomography (ct) imaging using objectively defined pet parameters to test for statistically significant changes before, during, and after external-beam radiation therapy (ebrt) and to identify the time points at which the changes occur.

METHODS:

The study enrolled 11 patients with intermediate-risk prostate cancer treated with ebrt, who were followed for up to 12 months after ebrt. The [(11)C]-choline pet scans were performed before treatment (baseline); at weeks 4 and 8 of ebrt; and at 1, 2, 3, 6, and 12 months after ebrt.

RESULTS:

Analysis of [(11)C]-choline uptake in prostate tissue before treatment resulted in a maximum standardized uptake value (suvmax) of 4.0 ± 0.4 (n = 11) at 40 minutes after injection. During week 8 of ebrt, the suvmax declined to 2.9 ± 0.1 (n = 10, p < 0.05). At 2 and 12 months after ebrt, suvmax values were 2.3 ± 0.3 (n = 10, p < 0.01) and 2.2 ± 0.2 (n = 11, p < 0.001) respectively, indicating that, after ebrt, maximum radiotracer uptake in the prostate was significantly reduced. Similar effects were observed when analyzing the tumour:muscle ratio (tmr). The tmr declined from 7.4 ± 0.6 (n = 11) before ebrt to 6.1 ± 0.4 (n = 11, nonsignificant) during week 8 of ebrt, to 5.6 ± 0.03 (n = 11, p < 0.05) at 2 months after ebrt, and to 4.4 ± 0.4 (n = 11, p < 0.001) at 12 months after ebrt.

CONCLUSIONS:

Our study demonstrated that intraprostatic [(11)C]-choline uptake in the 11 analyzed prostate cancer patients significantly declined during and after ebrt. The pet parameters SUVmax and tmr also declined significantly. These effects can be detected during radiation therapy and up to 1 year after therapy. The prognostic value of these early and statistically significant changes in intraprostatic [(11)C]-choline pet avidity during and after ebrt are not yet established. Future studies are indicated to correlate changes in [(11)C]-choline uptake parameters with long-term biochemical recurrence to further evaluate [(11)C]-choline pet changes as a possible, but currently unproven, biomarker of response.

 PubMed

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The Calgary Prostate Cancer Centre has the highest accrual for a novel ultrasound study in prostate cancer

“We have enrolled over 400 patients at our site, reaching our enrollment goal much faster than all other sites across North America. We are now planning on adding in 250 more patients to this trial because of the encouraging results found with the first arm of the trial. Our site tied with the highest accrual goal and surpassed all other sites to meet our enrollment goal.”

The study is a “Multi-Center trial of high-resolution transrectal ultrasound versus standard low-resolution transrectal ultrasound for the identification of clinically significant prostate cancer”

The only definitive method for diagnosing prostate cancer is through a prostate biopsy. This procedure includes the use of an ultrasound machine to guide both freezing needles and biopsy needles into the prostate. The ultrasound machine that is currently in use is a low-resolution ultrasound machine which means that although it is good at seeing the entire prostate gland to guide the needles, it is often unable to visualize the prostate in enough detail to be able to see different lesions and areas of concern within it. Thus, many biopsy samples are taken systematically with two samples from each section of the prostate. Recently a new ultrasound machine has been created that gives images of the prostate with much higher resolution, allowing the radiologist performing the biopsy to see details within the prostate that were previously inaccessible. A study using this new high-resolution ultrasound machine is being completed at the Prostate Cancer Centre to compare the adequacy of this new machine to detect prostate cancer over the standard low-resolution machine. Over 650 patients will be enrolled in this study!

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- Eric Hyndman