I-131 Therapy in Thyroid Cancer
Personalized radioactive iodine therapy for differentiated thyroid cancers
Iodine-131 Therapy for Differentiated Thyroid Cancer
Iodine-131 (I-131) therapy is a highly effective and well-established treatment for patients with differentiated thyroid cancer (DTC), including papillary and follicular thyroid carcinoma. At our center, I-131 therapy is delivered using a personalized, risk-adapted approach, ensuring that each patient receives the most appropriate treatment based on their disease profile.
Risk-Based Treatment Approach
Following thyroid surgery, patients are carefully evaluated and categorized into low-risk, intermediate-risk, or high-risk groups. This stratification is based on
Histopathological findings (tumor size, extrathyroidal extension, lymph node involvement, vascular invasion)
Serum thyroglobulin (Tg) levels
Serum anti-thyroglobulin antibodies
Diagnostic I-131 scan when required
USG neck
This risk classification helps determine: Whether I-131 therapy is required, The appropriate activity (dose) of I-131, The intensity of follow-up and surveillance
I-131 Therapy Tailored to Disease Stage
Patients are risk categorised based on hitopathological variant of tumor, extent of tumor in thyroid, extrathyroid involvement, lymph node involvement and distant metastasis
Low-risk patients
Intermediate-risk patients
High-risk patients
Each treatment plan is individualized, balancing maximum therapeutic benefit with patient safety
Patient Preparation Before Iodine-131 Therapy
Effective Iodine-131 therapy requires adequate stimulation of thyroid-stimulating hormone (TSH) to maximize radioiodine uptake by thyroid cells or residual disease. This can be achieved by two well-established preparation methods, chosen based on disease risk, patient suitability, and clinical indication.
Thyroxine Withdrawal- In this traditional approach, thyroxine is temporarily stopped for a few weeks (typically 3 to 4 weeks) prior to therapy, allowing the body’s natural TSH levels to rise.
Leads to high endogenous TSH levels, May cause short-term hypothyroid symptoms such as fatigue, weight gain, or low mood, Often preferred in high-risk disease or metastatic cases, where prolonged TSH elevation may be beneficial
Recombinant Human TSH (rhTSH) Method: This modern method uses recombinant TSH injections while the patient continues thyroxine therapy, Avoids hypothyroid symptoms, Maintains quality of life and daily functioning, Commonly used in low- and selected intermediate-risk patients, especially for remnant ablation or follow-up therapy
Personalized Approach: The choice between thyroxine withdrawal and recombinant TSH is individualized, taking into account: Disease stage and risk category, Serum thyroglobulin levels, Patient comorbidities and lifestyle consideration.
Our goal is to ensure optimal treatment effectiveness while prioritizing patient comfort and safety
Dynamic Risk Assessment & Follow-Up
Post-therapy follow-up is not static. We employ dynamic risk stratification, continuously reassessing patients based on their response to treatment, rather than relying solely on initial staging
Follow-up includes: Biochemical assessment, Serum thyroglobulin and anti-thyroglobulin antibody levels, Anatomical and functional imaging, Ultrasound, diagnostic whole-body scans, and PET/CT when indicated
Based on these findings, patients are categorized as having: Excellent response, Biochemical incomplete response, Structural incomplete response, Indeterminate response
Management of radio-iodine–refractory differentiated thyroid cancer (RAIR-DTC)
Radio-iodine–refractory differentiated thyroid cancer (RAIR-DTC) is managed with a combination of systemic therapy, local control measures, and supportive care. Management is individualized based on disease burden, rate of progression, symptoms, and molecular profile.
Confirming Radio-iodine Refractoriness -A thyroid cancer is considered RAI-refractory if one or more apply: No RAI uptake on diagnostic or post-therapy scans, Disease progression despite RAI uptake, Mixed uptake (some lesions avid, others not), Cumulative RAI dose with no meaningful response
Active Surveillance (Selected Patients)- Appropriate for asymptomatic, slowly progressive disease, Regular imaging and thyroglobulin monitoring, Delay systemic therapy until progression or symptoms
Local Therapies (For Oligoprogression or Symptom Control)-Surgery (isolated or threatening lesions), External beam radiotherapy, Stereotactic body radiotherapy (SBRT), Thermal ablation (RFA, cryoablation), Embolization for bone or liver metastases
Systemic Therapy Multikinase Inhibitors (Standard First-Line): Lenvatinib (preferred first-line), Sorafenib Targeted therapy: Dabrafenib ± Trametinib for BRAF V600E, Re-differentiation therapy, Theranostics: LU-177 FAPi therapy, Lu-177 DOTATATE therapy (based on tracer avidity)
Our Expert Doctors
About Doctor
Dr. Gayana Shankaramurthy
Nuclear Medicine and Theranostics Expert