Surgical Risk Prediction for Nasolacrimal Duct Obstruction in Radioactive Iodine-Treated Thyroid Cancer: A Nationwide Cohort Study

Eye-Related Adverse Events After I-131 Radioiodine Therapy: A Systematic Review of the Current Literature

OBJECTIVE

Although I-131 is relatively safe, there is limited focus on probable eye-related side effects after radioactive iodine (RAI) therapy. Thus, we aimed to provide evidence for the adverse outcomes of I-131, exclusively in patients with thyroid cancer.

METHODS

A systematic review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was designed to examine the ocular complications of RAI therapy. Databases including PubMed, Scopus, and Web of Science were searched until October 2023 with specific thyroid neoplasms, ophthalmology and iodine terms. After thorough screening and review, relevant data were extracted.

RESULTS

The database search yielded 3434 articles, which resulted in the final 28 eligible studies. These studies investigated ophthalmic symptoms following RAI therapy, classifying them as obstructive diseases (for example, nasolacrimal duct obstruction; median incidence rate: 6.8%), inflammatory symptoms (median incidence rate: 13%), and cataracts (median incidence rate: 2.5 and 5%). The most common time interval between RAI therapy and the onset of symptoms was within the first 12 months and then declined in the preceding years. A strong positive correlation was observed between higher I-131 doses of more than 100 to 150 mCi (3.7-5.55 GBq) and the risk of symptom development. Ages older than 45 also showed a significant association with nasolacrimal duct obstruction.

CONCLUSION

The risk of ophthalmic complications is associated with various factors, including the administration of high I-131 doses, age of more than 45 years, and time to event within the first 12 months. Considering these conditions may help enhance patient care and prevent adverse outcomes that may limit patients' quality of life.

Topical Application of Perchlorate: A Toxicity Study in Rats

PURPOSE

To investigate the ocular safety profile of topical perchlorate as a potential preventive treatment for nasolacrimal obstruction associated with excessive use of radioactive iodine therapy.

METHODS

Nine Wistar male rats (18 eyes) were randomly assigned to receive an ocular application (topical eye drop on the OD, 3 times a day for 5 days) consisting of either: 1) sterile saline solution, 2) 30 mg/ml NaClO4 or 3) 30 mg/ml KClO4. The rat eyes were examined daily for corneal cloudiness/clarity, discharge, mucous secretions, conjunctival injection, eyelid erythema, and/or changes in behavior. Seven days after the first dose, the rats were euthanized and OU were harvested, fixed, embedded in paraffin, and stained with H&E and Masson's trichrome using standard techniques.

RESULTS

The data collected over the 7 days revealed no behavior changes or ocular complications in any of the 3 study groups. Pathologic analysis of the corneas revealed normal findings on all groups without signs of inflammation, fibrosis, or any other abnormality, and no difference between the treated and control eyes.

CONCLUSIONS

The findings of this study suggest that the use of topical perchlorate is safe to use on eyes in high concentrations. The efficacy of this compound in minimizing fibrosis of the nasolacrimal sac and duct warrants further study.

Clinical characteristics of nasolacrimal duct obstruction after iodine therapy in differentiated thyroid cancer patients

OBJECTIVE

To analyze the clinical characteristics of differentiated thyroid cancer (DTC) patients with nasolacrimal duct obstruction (NLDO) after Iodine-131 (131I) therapy and provide guidance for clinical decision-making.

METHODS

Thirty-one DTC patients with NLDO were retrospectively enrolled from the Nuclear Medicine Department of Shanxi Bethune Hospital during follow-up of 131I therapy between June 2018 and March 2021. Eight hundred and seventy-one thyroid cancer patients during this period without NLDO after 131I therapy were enrolled as the control group. Clinical characteristics, including sex, age, dose, anti-thyroglobulin antibodies (TGAb), and metastatic lesions, were analyzed by χ2 test and logistic multifactor regression.

RESULTS

In the NLDO group and without NLDO group, there were statistically significant differences in gender, age, dose, and whether there was metastasis. Among the NLDO group, the proportion of women, age >55 years old, dose >5.55 GBq, and the presence of metastasis was higher, and the difference was statistically significant; There was no significant difference in the proportion of TGAb positive and negative patients based on 131I therapy (χ2 = 0.27, P = .782).Multivariate logistic regression analysis showed that sex (2.59), age (1.45), dose (2.36), and metastatic lesions (1.93) were all statistically significant influential factors of NLDO after iodine therapy. Significant differences were found in the incidence of NLDO between the number of treatment courses (χ2 = 23.541, P < .001). Prevalence rate of repeat radioiodine therapy (2 times or 3 times and more) is higher than 1 time.

CONCLUSION

Women patients over 55 who had metastatic lesions, and received a dose >5.55 GBq, were more likely to have NLDO. When determining therapeutic doses of 131I, doctors should weigh multiple factors and then give appropriate dosage and suggest that high risk populations be referred for appropriate ophthalmic surgical consultation, for timely diagnosis and therapy.