Smith Grace L, Smith Benjamin D, Giordano Sharon H, Shih Ya Chen T, Woodward Wendy A, Strom Eric A, Perkins George H, Tereffe Welela, Yu Tse Kuan, Buchholz Thomas A
Department of Breast Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Cancer. 2008 Mar 15;112(6):1371-9. doi: 10.1002/cncr.23307.
Hypothyroidism is a potential complication after radiation therapy (RT) when treatment fields include the thyroid. The authors assessed risk of hypothyroidism in breast cancer patients who were receiving RT to a supraclavicular field, which typically includes a portion of thyroid.
The authors identified 38,255 women (aged>65) without history of hypothyroidism from the Surveillance, Epidemiology, and End Results (SEER)-Medicare cohort diagnosed with stage 0-III breast cancer from 1992-2002 and 111,944 cancer-free controls. The authors compared hypothyroidism incidence among irradiated patients with 4+positive lymph nodes (4+LN, surrogate for supraclavicular RT) and no positive nodes (0 LN, surrogate for no supraclavicular RT), nonirradiated patients, and controls. Proportional hazards models tested associations of LN, RT, and breast cancer status with hypothyroidism.
The 5-year incidence of hypothyroidism was identical (14%) in irradiated patients with 4+LN, 0 LN, and nonirradiated patients (P=.52). After adjusting for sociodemographic and clinical characteristics, hypothyroidism risk was not increased in irradiated patients with 4+LN versus 0 LN (hazard ratio(HR)=1.04; 95% confidence interval (CI), 0.89-1.23). However, all patients, regardless of RT status, were more likely to be diagnosed with hypothyroidism compared with cancer-free controls (HR=1.21; 95% CI, 1.17-1.25).
Development of hypothyroidism is fairly common in older breast cancer survivors. Although supraclavicular irradiation does not appear to amplify risks, further studies on the role of routine thyroid function monitoring in all breast cancer patients regardless of treatment status may be warranted, given the excess risks compared with the general population.
当放疗（RT）的治疗野包括甲状腺时，甲状腺功能减退是放疗后的一种潜在并发症。作者评估了接受锁骨上野放疗的乳腺癌患者发生甲状腺功能减退的风险，锁骨上野通常包括部分甲状腺。
作者从监测、流行病学和最终结果（SEER）-医疗保险队列中确定了38,255名无甲状腺功能减退病史的女性（年龄>65岁），她们在1992年至2002年被诊断为0-III期乳腺癌，以及111,944名无癌对照者。作者比较了有4个及以上阳性淋巴结（4+LN，代表锁骨上放疗）和无阳性淋巴结（0 LN，代表无锁骨上放疗）的放疗患者、未放疗患者和对照者的甲状腺功能减退发生率。比例风险模型测试了淋巴结状态、放疗和乳腺癌状态与甲状腺功能减退的关联。
有4+LN的放疗患者、0 LN的放疗患者和未放疗患者的甲状腺功能减退5年发生率相同（14%）（P = 0.52）。在调整了社会人口统计学和临床特征后，有4+LN的放疗患者与0 LN的放疗患者相比，甲状腺功能减退风险没有增加（风险比[HR]=1.04；95%置信区间[CI]，0.89-1.23）。然而，与无癌对照者相比，所有患者，无论放疗状态如何，更有可能被诊断为甲状腺功能减退（HR=1.21；95%CI，1.17-1.25）。
甲状腺功能减退在老年乳腺癌幸存者中相当常见。虽然锁骨上照射似乎不会增加风险，但鉴于与一般人群相比存在额外风险，可能有必要对所有乳腺癌患者，无论治疗状态如何，进行常规甲状腺功能监测的作用进行进一步研究。
