Abstract

Context

Metastatic medullary thyroid cancer (MTC) is a rare malignancy with minimal treatment options. Many, but not all, MTCs express somatostatin receptors.

Objective

Our aim was to explore the role of ⁶⁸Ga-DOTA-somatostatin analogue (SSA) PET/CT in patients with metastatic MTC, and to determine their eligibility for peptide receptor radionuclide therapy (PRRT).

Methods

We retrospectively identified patients with metastatic MTC who had ⁶⁸Ga-DOTA-SSA PET/CT at five centers. We collected characteristics on contrast-enhanced CT, ⁶⁸Ga-DOTA-SSA and ¹⁸F-FDG PET/CT. The efficacy of PRRT was explored in a subgroup of patients. Kaplan-Meier analysis was used to estimate time to treatment failure (TTF) and overall survival (OS).

Results

Seventy-one patients were included (10 local recurrence, 61 distant disease). Of the patients with distant disease, 16 (26%) had ≥50% of disease sites with tracer avidity greater than background liver, including 10 (10/61, 16%) with >90%. In 19 patients with contemporaneous contrast-enhanced CT, no disease regions were independently identified on ⁶⁸Ga-DOTA-SSA PET/CT. Thirty-five patients had an ¹⁸F-FDG PET/CT, with ¹⁸F-FDG positive/ ⁶⁸Ga-DOTA-SSA negative metastases identified in 15 (43%). Twenty-one patients had PRRT with a median TTF of 14 months (95%CI 8-25) and a median OS of 63 months (95%CI 21–not reached). Of the entire cohort, the median OS was 323 months (95%CI 152-not reached). Predictors of poorer overall survival included a short calcitonin doubling-time (≤24 months), strong ¹⁸F-FDG avidity and age ≥60 years.

Conclusions

The prevalence of high tumour avidity on ⁶⁸Ga-DOTA-SSA PET/CT is low in the setting of metastatic MTC; nevertheless, PRRT may still be a viable treatment option in select patients.

中文翻译：

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转移性甲状腺髓样癌：68 镓-DOTA-生长抑素类似物 PET/CT 和肽受体放射性核素治疗的作用

摘要

语境

转移性甲状腺髓样癌 (MTC) 是一种罕见的恶性肿瘤，治疗选择很少。许多（但不是全部）MTC 表达生长抑素受体。

客观的

我们的目的是探索⁶⁸ Ga-DOTA-生长抑素类似物 (SSA) PET/CT 在转移性 MTC 患者中的作用，并确定他们是否适合肽受体放射性核素治疗 (PRRT)。

方法

我们回顾性地确定了在五个中心进行了⁶⁸ Ga-DOTA-SSA PET/CT 的转移性 MTC 患者。我们收集了对比增强 CT、⁶⁸ Ga-DOTA-SSA 和¹⁸ F-FDG PET/CT 的特征。在一个亚组患者中探索了 PRRT 的疗效。Kaplan-Meier 分析用于估计治疗失败时间 (TTF) 和总生存期 (OS)。

结果

包括 71 名患者（10 名局部复发，61 名远处疾病）。在有远处疾病的患者中，16 名 (26%) 有≥50% 的病灶具有大于背景肝脏的示踪剂亲和力，其中 10 名 (10/61, 16%) 具有 >90%。在 19 名同时进行对比增强 CT 的患者中，没有在⁶⁸ Ga-DOTA-SSA PET/CT上独立识别出疾病区域。35 名患者进行了¹⁸ F-FDG PET/CT，其中¹⁸ F-FDG 阳性/ ⁶⁸Ga-DOTA-SSA 阴性转移有 15 例（43%）。21 名患者接受 PRRT，中位 TTF 为 14 个月（95%CI 8-25），中位 OS 为 63 个月（95%CI 21-未达到）。在整个队列中，中位 OS 为 323 个月（95% CI 152-未达到）。总生存期较差的预测因素包括较短的降钙素倍增时间（≤24 个月）、强烈的¹⁸ F-FDG 亲和力和年龄≥60 岁。

结论

在转移性 MTC 的情况下，⁶⁸ Ga-DOTA-SSA PET/CT上高肿瘤亲和力的流行率较低；尽管如此，PRRT 可能仍然是特定患者的可行治疗选择。