From the Research
For papillary thyroid carcinoma with positive margins, the recommended adjuvant therapy is radioactive iodine (RAI) treatment, typically with I-131 at doses ranging from 30-100 mCi for intermediate-risk patients or 100-200 mCi for higher-risk cases, as supported by the most recent study 1.
Key Considerations
- The goal of adjuvant therapy is to reduce the likelihood of local recurrence and improve long-term outcomes, particularly in patients with positive margins, which indicates incomplete tumor resection and increased recurrence risk.
- RAI therapy works by destroying residual thyroid tissue and microscopic cancer cells that may remain after surgery, as these cells retain the ability to concentrate iodine.
- The choice of RAI dose should be individualized based on the patient's risk factors, including the size of the metastatic lymph nodes, resection margin status, and post-RAI suppressed thyroglobulin level, as identified as independent prognostic factors for locoregional recurrence-free survival (LRRFS) in the study 1.
Treatment Protocol
- RAI treatment should be administered 4-6 weeks after thyroidectomy, following thyroid hormone withdrawal or with recombinant TSH stimulation to achieve TSH levels >30 mIU/L.
- Prior to RAI, patients should follow a low-iodine diet for 1-2 weeks.
- TSH suppression therapy with levothyroxine is also essential, targeting TSH levels between 0.1-0.5 mIU/L for intermediate-risk patients.
- Close monitoring with thyroglobulin measurements, neck ultrasound, and whole-body scans should follow at 6-12 month intervals.
Evidence Summary
- The study 1 demonstrated that 75% of patients with PTC with other organ invasions could achieve long-term survival without recurrence after adjuvant RAI, highlighting the effectiveness of RAI therapy in improving outcomes.
- The study 2 suggested that RAI adjuvant therapy may not be necessary for patients with small tumors, but this finding is not directly applicable to patients with positive margins.
- The study 3 found that higher administered activities of RAI were associated with less structural persistent response in older patients, but this finding is not directly relevant to the treatment of patients with positive margins.
- The study 4 reported that recurrence-free survival in positive-margin patients was 71% at 10 years, highlighting the need for effective adjuvant therapy in this patient population.
- The study 5 provided an overview of the management of papillary thyroid cancer, including the role of RAI adjuvant therapy, but did not provide specific guidance on the treatment of patients with positive margins.