Bal C S, Kumar Ajay, Pant G S
Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India.
J Clin Endocrinol Metab. 2004 Apr;89(4):1666-73. doi: 10.1210/jc.2003-031152.
Remnant ablation can be achieved by either administering an empiric fixed dose or using dosimetry-guided techniques. Because of the technical and logistic difficulties, most centers have adapted the fixed-dose or standard-dose technique for remnant ablation using (131)I. In the late 1970s, low-dose (131)I remnant ablation was introduced, and subsequently many centers confirmed the effectiveness of such therapy. However, the optimal dose (administered activity) of (131)I for remnant ablation is not yet settled. In a randomized clinical trial to find out the smallest possible effective dose for remnant ablation in cases of differentiated thyroid carcinoma, between July 1995 and January 2002, 565 patients were randomized into eight groups according to (131)I administered activity, starting at 15 mCi and increasing activity in increments of 5 mCi until 50 mCi. In the postrandomization phase, 56 patients were excluded from the study for various reasons, and final analysis was done with 509 patients. The mean age of the patients was 37.5 +/- 12.7 yr with a female to male ratio of 2.6. The surgical procedure was total/near-total thyroidectomy in 72% and subtotal or hemithyroidectomy in the rest. Histology was papillary thyroid carcinoma in 80.6% of patients and follicular thyroid carcinoma in the rest. With one dose of (131)I, remnant ablation was achieved in 59.6, 63.6, 81.4, 83.6, 79.4, 78.3, 84.4, and 81.8% of patients in the 15- to 50-mCi groups, respectively (overall ablation rate, 77.6%). The successful ablation rate was statistically different in patients receiving less than 25 mCi of (131)I compared with those receiving at least 25 mCi [63 of 102 (61.8%) vs. 332 of 407 (81.6%); P = 0.006]. However, there was no significant intergroup difference in outcome among patients receiving 25-50 mCi of (131)I. Patients with small tumor size (</=5 cm), adequate surgery (total/near-total thyroidectomy), and radioiodine neck uptake of less than or equal to 10% had odds ratios of 2.4 [confidence interval (CI), 1.3-3.98], 2.6 (CI, 1.6-4.2), and 2.2 (CI, 1.4-3.5), respectively, for successful remnant ablation. Patients receiving at least 25 mCi of (131)I had a three times better chance of getting remnant ablation than patients receiving lesser activity of (131)I. Any activity of (131)I between 25 and 50 mCi appears to be adequate for remnant ablation.
残留组织消融可通过给予经验性固定剂量或使用剂量测定引导技术来实现。由于技术和后勤方面的困难，大多数中心采用固定剂量或标准剂量技术使用（131）I进行残留组织消融。20世纪70年代末，引入了低剂量（131）I残留组织消融，随后许多中心证实了这种治疗方法的有效性。然而，用于残留组织消融的（131）I的最佳剂量（给药活度）尚未确定。在一项旨在找出分化型甲状腺癌病例中残留组织消融的最小有效剂量的随机临床试验中，1995年7月至2002年1月期间，565例患者根据（131）I给药活度被随机分为八组，起始活度为15 mCi，以5 mCi的增量增加活度，直至50 mCi。在随机分组后阶段，56例患者因各种原因被排除在研究之外，最终对509例患者进行了分析。患者的平均年龄为37.5±12.7岁，女性与男性的比例为2.6。72%的患者接受了全甲状腺切除/近全甲状腺切除术，其余患者接受了次全甲状腺切除或半甲状腺切除术。组织学检查显示，80.6%的患者为乳头状甲状腺癌，其余为滤泡状甲状腺癌。在15至50 mCi组中，分别有59.6%、63.6%、81.4%、83.6%、79.4%、78.3%、84.4%和81.8%的患者通过一剂（131）I实现了残留组织消融（总体消融率为77.6%）。接受少于25 mCi（131）I的患者与接受至少25 mCi（131）I的患者相比，成功消融率在统计学上存在差异[102例中的63例（61.8%）对407例中的332例（81.6%）；P = 0.006]。然而，接受25至50 mCi（131）I的患者之间在结局方面没有显著的组间差异。肿瘤体积小（≤5 cm）、手术充分（全甲状腺切除/近全甲状腺切除术）且放射性碘颈部摄取小于或等于10%的患者实现残留组织成功消融的优势比分别为2.4[置信区间（CI），1.3 - 3.98]、2.6（CI，1.6 - 4.2）和2.2（CI，1.4 - 3.5）。接受至少25 mCi（131）I的患者实现残留组织消融的机会是接受较低活度（131）I患者的三倍。25至50 mCi之间的任何（131）I活度似乎都足以实现残留组织消融。
