碘—131全身掃描與血清甲狀腺球蛋白測定偵測分化良好型甲狀腺癌復發或轉移之價值

背景：治療後之分化良好型甲狀腺癌(well-differentiated thyroid carcinoma; WDTC)通常以碘-131全身掃描（131Iwhole body scan;131I WBS）及血清甲狀腺球蛋白(serum thyrogobulin; Tg）來追蹤其復發或轉移。本研究針對本院WDTC病患所實施的Tg測定及131I WBS結果作回溯性分析及比較，期能評估此兩種方法對WDTC病患復發或轉移病灶的偵測價值及建立預測WDTC復發或轉移之Tg正常臨界值(cut-off value)。方法：112例曾接受過甲狀腺全切除或近甲狀腺全切除術及至少100mCi之碘-131成功地將腫瘤殘餘組織摘除的WDTC病患，分別施以系列131I　WBS檢查及血清Tg測定；再分析131I WBS對其中18例具復發或轉移者之偵測靈敏度與專一度，並採用Tg=1，2，4,8μg/L作為臨界值，分別計算於復發或轉移性病灶偵測之靈敏度與專一度，選擇適當的Tg值，作為正常臨界值。結果：18例具復發或轉移的患者中，有13例其131I WBS呈現陽性，偵測靈敏度為72%(13/18)；94例未見復發或轉移之病患中，有88例呈現陰性，偵測專一度為94%(88/94)。18例具復發或轉移的患者血清Tg平均值為171.8±110.7μg/L,94例未見復發或轉移之病患血清Tg平均值為1.8±0.5μg/L,兩相比較具統計學上之顯著差異；採用不同的Tg作為正常臨界值，有不同的陽性檢測率；以Tg≤1μg/L作為臨界值，偵測靈敏度為94%(17/18)，專一度為78%(73/94)，以2μg/L作為臨界值，靈敏度為89%(16/18)，專一度為89%(84/94)，以4μg/L作為臨界值，靈敏度為72%(13/18)，專一度為96%(90/94)，以8μg/L為臨界值，靈敏度為67%(12/18)，專一度為98%(92/94)。若以131I WBS結合Tg≤2μg/L作為正常臨界值，則偵測之靈敏度約可達94%(17/18)，專一度亦達91%(86/94)。結論：131I WBS對WDTC復發或轉移病灶的偵測具高專一性、低靈敏度，而Tg對WDTC復發或轉移病灶的偵測具高靈敏度，兩者具互補作用，若配合Tg≤2μg/L作為正常臨界值，則可以有效地提高偵測WDTC復發或轉移病灶靈敏度及專一性。當然，對Tg分界值的設定則須參考病人預後危險因數。

關鍵字

分化良好型甲狀腺癌；碘—131全身掃描；血清甲狀腺球蛋白

並列摘要

Background: 131I whole body scan (WBS) and serum thyrogobulin (Tg) measurement are routinely used to follow up the recurrence or metastasis of well-differentiated thyroid carcinoma (WDTC). This study retrospectively analyzed WDTC patients by using the results of WBS and Tg to determine the optimal cut-off value to predict the recurrence or metastasis of WDTC. Methods: WBS and serum Tg measurements were examined in 112 WDTC patients who received total or near total thyroidectomy and at least 100 mCi of 131I thyroid ablation therapy. Of them, 18 patients were diagnosed with recurrences or metastases. Sensitivity and specificity for presence of disease using WBS were calculated. In addition, sensitivity and specificity of serum Tg using four cut-off values (Tg= 1,2,4, or 8 g/L) were measured. The most optimal cut-off value of Tg by both WBS and Tg to predict the recurrence or metastasis of WDTC was determined. Results: For the recurrent group, 12 of 18 had positive finding in WBS; For the non-recurrent group, 88 of 94 negative finding in WBS. The sensitivity, specificity of the WBS for detecting recurrences and metastases were 72% (12/18) and 94% (88/94) retrospectively. For the recurrent group, 171.8 ± 110.7 g/L of serum Tg was measured,and 1.8 ± 0.5 g/L of serum Tg was measured in the non-recurrent group. Variable detective rates were found when the cut-off values Tg were selected differently. The sensitivity, specificity of serum Tg for detecting disease recurrence were 94% and 78% when the cut-off value was set at 1μ g/L; 89% vs. 89% at 2 g/L; 72% vs. 96% at 4 g/L and 67% vs. 98% at 8 g/L. Conclusions: 131I WBS has a high sensitivity, but a low specificity for the detection of recurrent or metastatic WDTC.Both WBS and Tg measurement are complementary for the detection of disease. Our results suggest that using WBS and 2 g/L cut-off value of Tg could be optimal for the detection of recurrent or metastatic WDTC. However, patients’ prognostic risk factor should be taken in account in this regard.

並列關鍵字

well-differentiated thyroid carcinoma, radioiodine whole body scan, serum thyroglobulin

國際替代計量

碘—131全身掃描與血清甲狀腺球蛋白測定偵測分化良好型甲狀腺癌復發或轉移之價值

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