Head and Neck Service, Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
Cancer. 2011 Oct 1;117(19):4439-46. doi: 10.1002/cncr.26070. Epub 2011 Mar 22.
American Thyroid Association guidelines currently recommend the selective use of radioactive iodine (RAI) therapy in patients with well differentiated thyroid cancer (WDTC). Despite these guidelines, RAI ablation has been used routinely in all but the very lowest risk patients with thyroid cancer over the last 30 years. The objective of this study was to evaluate patterns of RAI use and elevated risk of secondary primary malignancies (SPM) in patients with low-risk (T1N0) WDTC.
The Surveillance, Epidemiology, and End Results (SEER) database was used to analyze trends in RAI use over time in the United States. To determine the excess risk of SPM, the standardized incidence ratio (SIR) and excess absolute risk (EAR) of various cancers were calculated in the 2 cohorts. Between 1973 and 2007, 37,176 patients with WDTC were followed in the SEER Program, equating to 408,750 person-years at risk (PYR). In total, 14,589 patients received RAI, and SPMs were observed in 3223 patients.
During the study period, the rate of RAI use in patients with low-risk (T1N0) WDTC increased from 3.3% to 38.1%. For low-risk patients, the SIR of SPM was 1.21 (95% confidence interval [CI], 0.93-1.54), and the EAR was 4.6 excess cases per 10,000 PYR. SPM with significantly elevated risk because of RAI were salivary gland malignancies (SIR = 11.13; 95% CI, 1.35-40.2) and leukemia (SIR = 5.68; 95% CI, 2.09-12.37). The excess risk of leukemia was significantly greater in patients aged <45 years (SIR = 5.32; 95% CI, 2.75-9.30) compared with the excess risk in older patients (SIR = 2.26; 95% CI, 1.43-3.39).
The increased risk of a SPM in patients with low-risk (T1N0) WDTC, along with a lack of data demonstrating improved survival outcomes with adjuvant RAI, provide a compelling argument in favor of rationing the use of RAI in this patient population.
美国甲状腺协会指南目前建议在分化型甲状腺癌（WDTC）患者中选择性使用放射性碘（RAI）治疗。尽管有这些指南，但在过去的 30 年中，除了甲状腺癌风险极低的患者外，RAI 消融术已常规用于所有患者。本研究的目的是评估低危（T1N0）WDTC 患者中 RAI 使用情况和继发性原发性恶性肿瘤（SPM）的升高风险。
使用监测、流行病学和最终结果（SEER）数据库分析美国 RAI 使用随时间的变化趋势。为了确定 SPM 的超额风险，在 2 个队列中计算了各种癌症的标准化发病比（SIR）和超额绝对风险（EAR）。在 1973 年至 2007 年间，SEER 计划共随访了 37176 例 WDTC 患者，相当于 408750 人年风险（PYR）。共有 14589 例患者接受了 RAI，3223 例患者观察到 SPM。
在研究期间，低危（T1N0）WDTC 患者接受 RAI 的比例从 3.3%增加到 38.1%。对于低危患者，SPM 的 SIR 为 1.21（95%置信区间[CI]，0.93-1.54），EAR 为每 10000PYR 4.6 例超额病例。由于 RAI 而导致 SPM 风险显著增加的是唾液腺癌（SIR=11.13；95%CI，1.35-40.2）和白血病（SIR=5.68；95%CI，2.09-12.37）。与老年患者（SIR=2.26；95%CI，1.43-3.39）相比，<45 岁患者的白血病超额风险（SIR=5.32；95%CI，2.75-9.30）显著更高。
低危（T1N0）WDTC 患者 SPM 的风险增加，以及缺乏数据表明辅助 RAI 可改善生存结果，这有力地支持了对该患者人群使用 RAI 进行配给的观点。
