Utility of adjuvant radioactive iodine therapy after reoperation in papillary thyroid carcinoma with cervical lymph node recurrence

• Published in: Japanese journal of radiology Vol. 41; no. 10; pp. 1148 - 1156
• Main Authors: Zhang, Yaqi, Zhu, Xiqun, Fan, Qianyu, Huang, Qiuyi, Tu, Yun, Jiang, Liang, Zhang, Zixiong, Chen, Jian
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01-10-2023; Springer Nature B.V
• Subjects: Biochemistry; Cervical carcinoma; Chi-square test; Imaging; Iodine; Iodine radioisotopes; Lymph nodes; Medical prognosis; Medicine; Medicine & Public Health; Multivariate analysis; Nuclear Medicine; Original Article; Papillary thyroid carcinoma; Prognosis; Radiology; Radiotherapy; Regression models; Statistical models; Subgroups; Therapy; Thyroglobulin; Thyroid; Thyroid cancer; Papillary thyroid carcinoma (PTC); Progression-free survival (PFS); Extranodal invasion; Radioactive iodine therapy (RAI); Lymph node (LN) recurrence
• ISSN: 1867-1071; 1867-108X
• DOI: 10.1007/s11604-023-01438-7

Purpose
The aim of this study was to evaluate the utility of RAI therapy after reoperation for patients with LN relapse.
Materials and methods
We retrospectively evaluated PTC patients who had undergone reoperation due to cervical LN recurrence. We used the chi-square test, Fisher’s exact test, Student’s t test and the Mann–Whitney U test to compare characteristics between patients retreated with RAI and those who did not receive RAI after reoperation. A multivariate logistic regression model was used to determine the association between RAI and biochemical response. By means of the Kaplan–Meier estimator and a multivariate Cox proportional hazard model, we assessed whether administration of RAI after reoperation is associated with improved prognosis.
Results
RAI therapy was closely associated with a superior biochemical response in all selected patients according to both univariate (p = 0.012) and multivariate analyses (p = 0.020). Thirteen of 97 patients developed a second recurrence or progression of structural disease during follow-up. A Kaplan–Meier progression-free survival (PFS) curve showed that high post-retreatment thyroglobulin (Tg) levels (≥ 1 ng/mL) were associated with unfavourable prognosis (p = 0.0172). In the subgroup analysis, univariate analysis revealed that only patients without extranodal invasion who received adjuvant RAI therapy achieved better PFS than those who did not receive RAI therapy (p = 0.0203). Multivariate analysis showed that RAI (p = 0.045) also improved PFS in patients without extranodal invasion.
Conclusions
Adjuvant RAI after reoperation for PTC recurrence/persistence was associated with a favourable biochemical response and tended to increase PFS. Specifically, it was significantly associated with improved PFS only in patients without extranodal extension.