Division of Radiation Oncology, Department of Oncology, University of Alberta, Cross Cancer Institute, Edmonton, AB.
Curr Oncol. 2013 Apr;20(2):104-10. doi: 10.3747/co.20.1217.
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.
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.
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.
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.
本研究旨在通过正电子发射断层扫描（PET）/计算机断层扫描（CT）成像，利用客观定义的 PET 参数，以相对较高的灵敏度和特异性分析前列腺癌患者（11）C-胆碱的摄取特性，以测试外照射放疗（EBRT）前后的统计学显著变化，并确定发生变化的时间点。
本研究纳入了 11 例接受 EBRT 治疗的中危前列腺癌患者，在 EBRT 后长达 12 个月进行随访。在治疗前（基线）、EBRT 的第 4 周和第 8 周以及 EBRT 后 1、2、3、6 和 12 个月进行（11）C-胆碱 PET 扫描。
在治疗前分析前列腺组织中的（11）C-胆碱摄取，在注射后 40 分钟时得出最大标准化摄取值（SUVmax）为 4.0±0.4（n=11）。在 EBRT 的第 8 周，SUVmax 下降至 2.9±0.1（n=10，p<0.05）。在 EBRT 后 2 个月和 12 个月时，SUVmax 值分别为 2.3±0.3（n=10，p<0.01）和 2.2±0.2（n=11，p<0.001），表明 EBRT 后，前列腺中最大放射性示踪剂摄取显著减少。当分析肿瘤：肌肉比值（TMR）时，也观察到类似的效果。TMR 从 EBRT 前的 7.4±0.6（n=11）下降到 EBRT 第 8 周的 6.1±0.4（n=11，无显著性），到 EBRT 后 2 个月的 5.6±0.03（n=11，p<0.05），到 EBRT 后 12 个月的 4.4±0.4（n=11，p<0.001）。
我们的研究表明，在 11 例分析的前列腺癌患者中，前列腺内（11）C-胆碱的摄取在 EBRT 期间和之后显著下降。SUVmax 和 TMR 等 PET 参数也显著下降。这些影响可在放疗期间和治疗后 1 年内检测到。EBRT 期间和之后前列腺内（11）C-胆碱 PET 摄取活性的这些早期和统计学显著变化的预后价值尚未确定。需要进一步的研究来将（11）C-胆碱摄取参数的变化与长期生化复发相关联，以进一步评估（11）C-胆碱 PET 变化作为反应的可能但目前未经证实的生物标志物。
