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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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Working to include Yukoners in APCaRI

APCaRI, represented by John Lewis and Catalina Vasquez, met with many Yukoners in Whitehorse recently to discuss the potential of including the North of 60 men in the registry and their samples in the biorepository. Sean Secord (photographed with John and Catalina), formerly with the Yukon Hospitals Foundation, talked with John on CBC Whitehorse radio about the challenges that Yukoners with cancer, and their families, have to manage and overcome to get testing and treatment. They are formidable; a recent article by Simkin et al., 2017 evaluated cancer mortality rates in the Yukon from 1999 to 2013 and found that they were elevated for prostate, female breast and lung, and colorectal cancers compared to both urban and rural populations in Canada South of the Yukon. The authors suggested that the high Yukon rates are, in part, due to the high percentage of Yukoners living in rural and very remote communities, making it necessary for patients to have to travel long distances for diagnoses and treatment. But even if the cancer patient lives in Whitehorse, (Yukon capital, population 25 085), cancer care options are limited due in part to a lack of oncologists and the specialized equipment needed.
John and Catalina met and had stimulating discussions with many people dedicated to improving cancer care in the North including the Yukon Ride for Dad organizers, representatives from the medical and laboratory communities and people living with cancer, and their families.
APCaRI is determined to find a way to include the Yukon men in the registry so that their valuable medical information and samples can be added to the prostate cancer research initiative and be an important part of improving prostate cancer diagnosis, treatment and care.

- Perrin Beatty