Department of Nuclear Medicine, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
Ann Nucl Med. 2012 Aug;26(7):551-8. doi: 10.1007/s12149-012-0609-0. Epub 2012 May 30.
Tumor recurrence of colorectal cancers (CRC) is generally followed up by analyses of the serum carcinoembryonic antigen (CEA) levels. However, recent evidence suggests that tumor recurrence can also be visualized by 18F-fluoro-deoxyglucose emission tomography/computed tomography (FDG-PET/CT) in patients with normal CEA levels. We retrospectively evaluated the diagnostic performance of FDG-PET/CT in patients with suspected recurrence of CRC by comparing PET/CT performance in patients with normal CEA levels with PET/CT performance in patients with elevated CEA levels.
A total of 235 patients with CRC who had been treated with surgery and/or chemotherapy/radiotherapy underwent PET/CT for the detection of tumor recurrence. The patients [96 females and 139 males; age (mean ± SD) 59.9 ± 12.6 years; range 18-85] were divided into 2 groups based on whether their CEA levels were normal (<5 ng/ml) (Group 1, n = 118) or elevated (>5 ng/ml) (Group 2, n = 117). All of the patients had suspected recurrence based on raised CEA levels, clinical symptoms, and/or tumor detection using other imaging modalities.
Of the 235 patients, 172 (73.1 %) had disease recurrence confirmed by a pathological examination (either biopsy or surgical exploration) or clinical follow-up studies. The FDG-PET/CT study yielded a true positive in detecting recurrence in 169 (71.9 %) patients, a true negative in 53 (22.5 %) patients, a false negative in 3 (1.2 %) patients and a false positive in 10 (4.2 %) patients. CRC recurrence was detected in 64.4 % (76/118) and 88 % (103/117) patients in Group 1 and Group 2 with FDG-PET/CT, respectively. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of the FDG-PET/CT study for establishing recurrence were 100, 84, 89.4, 100 and 93.2 %, respectively, for Group 1; by contrast, these parameters were 97.1, 84.6, 98, 78.5 and 95.7 %, respectively, for Group 2. The number of patients with hepatic and extra-hepatic metastases, such as lung and abdominal lymph node metastasis, detected with FDG-PET/CT was significantly different in Group 1 than in Group 2; however, the number of patients with local recurrence and peritoneal implants detected with FDG-PET/CT was not different between the two groups.
FDG-PET/CT can accurately detect tumor recurrence in patients with suspected recurrent CRC, even for patients with normal CEA levels.
结直肠癌（CRC）的肿瘤复发通常通过分析血清癌胚抗原（CEA）水平来进行随访。然而，最近的证据表明，对于 CEA 水平正常的患者，18F-氟代脱氧葡萄糖发射断层扫描/计算机断层扫描（FDG-PET/CT）也可以观察到肿瘤复发。我们通过比较 CEA 水平正常组和 CEA 水平升高组的 PET/CT 表现，回顾性评估了 FDG-PET/CT 在疑似 CRC 复发患者中的诊断性能。
235 例接受手术和/或化疗/放疗治疗的 CRC 患者接受了 PET/CT 检测以发现肿瘤复发。患者[96 名女性和 139 名男性；年龄（均值±标准差）59.9±12.6 岁；范围 18-85]根据 CEA 水平是否正常（＜5ng/ml）（第 1 组，n=118）或升高（＞5ng/ml）（第 2 组，n=117）分为 2 组。所有患者均基于升高的 CEA 水平、临床症状和/或其他成像方式检测到的肿瘤进行可疑复发。
在 235 例患者中，172 例（73.1%）通过病理检查（活检或手术探查）或临床随访研究证实存在疾病复发。FDG-PET/CT 研究在 169 例（71.9%）患者中检测到了真正的阳性，在 53 例（22.5%）患者中检测到了真正的阴性，在 3 例（1.2%）患者中检测到了假阴性，在 10 例（4.2%）患者中检测到了假阳性。在第 1 组和第 2 组中，分别有 64.4%（76/118）和 88%（103/117）的患者通过 FDG-PET/CT 检测到 CRC 复发。FDG-PET/CT 研究对确立复发的敏感性、特异性、阳性预测值（PPV）、阴性预测值（NPV）和准确性分别为 100、84、89.4、100 和 93.2%，用于第 1 组；相比之下，这些参数分别为 97.1、84.6、98、78.5 和 95.7%，用于第 2 组。在第 1 组中，FDG-PET/CT 检测到的肝内和肝外转移，如肺和腹部淋巴结转移的患者数量明显多于第 2 组；然而，两组之间通过 FDG-PET/CT 检测到的局部复发和腹膜种植的患者数量没有差异。
FDG-PET/CT 可准确检测疑似复发性 CRC 患者的肿瘤复发，即使是 CEA 水平正常的患者。
