Cytogenetic Damage Induced by Radioiodine Therapy: A Follow-Up Case Study.

Area of Science:

• Oncology
• Genetics
• Radiology

Background:

• Radioiodine therapy (RIT) is used for differentiated thyroid cancer (DTC).
• Assessing RIT-induced toxicity and cytogenetic damage is crucial for patient safety.
• A whole-body dose of 2 Gy is considered a safe limit for RIT.

Purpose of the Study:

• To evaluate RIT-induced cytogenetic damage in rare DTC cases.
• To assess long-term cytogenetic risk and prognosis following RIT.
• To investigate the utility of cytogenetic biodosimetry in personalized RIT planning.

Main Methods:

• Analysis of chromosome aberrations (CA) in peripheral blood lymphocytes (PBL) using conventional assays, FISH, and mFISH.
• Conversion of CA data to whole-body dose, considering dose rate effects.
• Follow-up cytogenetic analysis in a pediatric DTC patient and an adult DTC patient.

Main Results:

• mFISH revealed an increase in aberrant cell frequency after RIT, predominantly unstable aberrations.
• Stable CA, indicative of long-term risk, remained largely unchanged during follow-up.
• Whole-body doses did not exceed the 2 Gy safety threshold, indicating low RIT-attributable risk.

Conclusions:

• RIT in these rare DTC cases posed a low risk of significant long-term cytogenetic damage.
• Individualized treatment planning using cytogenetic biodosimetry is recommended for optimal RIT outcomes.
• The study supports a good long-term prognosis for patients undergoing RIT when managed appropriately.