The purpose of this study was to investigate the diagnostic and prognostic value of ¹⁸F-FDG PET/CT for surveillance imaging in patients treated for stage III Merkel cell carcinoma (MCC). Methods: This retrospective study included 61 consecutive stage III MCC patients who were clinically asymptomatic and underwent surveillance ¹⁸F-FDG PET/CT. Findings were correlated with either pathology or clinical/imaging follow-up. The median follow-up period was 4.8 y. Statistical analyses were performed. Results: ¹⁸F-FDG PET/CT detected unsuspected recurrences in 33% patients (20/61) with lesion-based sensitivity, specificity, and accuracy of 92%, 93%, and 93%, respectively. The mean ± SD SUV for malignant and benign lesions was 7.5 ± 3.9 and 3.8 ± 2.0, respectively. Unknown distant metastases, as first recurrence site, were noted in 12 of 61 patients. Those with positive disease on ¹⁸F-FDG PET/CT within 1 y of definitive treatment had relatively worse overall survival (P < 0.0001). After adjustment on stage, risk of death increased with a higher SUV_max (hazard ratio for 1 unit = 1.17; P = 0.006) and with a higher number of positive lesions on ¹⁸F-FDG PET/CT (hazard ratio for 1 additional lesion = 1.60; P < 0.001). Conclusion: Postdefinitive treatment surveillance ¹⁸F-FDG PET/CT scanning detects unsuspected recurrences and has prognostic value. Inclusion of ¹⁸F-FDG PET/CT within the first 6 mo after definitive treatment would be appropriate for surveillance and early detection of recurrence. Our data merit further studies to evaluate the prognostic implications.

本研究的目的是探讨¹⁸ F-FDG PET/CT 对接受 III 期默克尔细胞癌 (MCC) 治疗的患者进行监测成像的诊断和预后价值。方法：这项回顾性研究纳入了 61 名连续的 III 期 MCC 患者，这些患者没有临床症状并接受了^18F -FDG PET/CT 监测。结果与病理学或临床/影像学随访相关。中位随访期为 4.8 年。进行了统计分析。结果： ¹⁸F-FDG PET/CT 在 33% (20/61) 患者中检测到意外复发，基于病变的敏感性、特异性和准确性分别为 92%、93% 和 93%。恶性和良性病变的平均 ± SD SUV 分别为 7.5 ± 3.9 和 3.8 ± 2.0。61 名患者中有 12 名发现未知远处转移，作为第一个复发部位。^{根治性治疗后 1 年内18} F-FDG PET/CT疾病阳性的患者总生存期相对较差 ( P < 0.0001)。在阶段调整后，死亡风险随着 SUV_最大值（1 个单位的风险比 = 1.17；P = 0.006）和¹⁸ F-FDG PET/CT阳性病灶数量的增加（1 个额外病灶的风险比）增加而增加= 1.60; P< 0.001)。结论：最终治疗后监测^18F -FDG PET/CT 扫描可检测出未预料到的复发并具有预后价值。在根治性治疗后的前 6 个月内进行^18F -FDG PET/CT 将适用于监测和早期发现复发。我们的数据值得进一步研究以评估预后影响。