Outcomes of Low-Risk Differentiated Thyroid Cancer (DTC) without Radioactive Iodine (RAI) Ablation Therapy Post-Thyroidectomy: An Experience from a Tertiary Centre in Karachi.

Abstract

Objective: To assess the outcomes of low-risk differentiated thyroid cancer (DTC) with tumour size 1 to 4 cm post-thyroidectomy in patients who never received radioactive iodine (RAI) ablation and to compare the outcomes with those who received RAI therapy.

Study design: Observational study. Place and Duration of the Study: Department of Nuclear Medicine, Karachi Institute of Radiotherapy and Nuclear Medicine (KIRAN) Hospital, Karachi, Pakistan, from January 2016 to December 2020.

Methodology: A total of 130 consecutive patients of low-risk DTC of both genders aged between 18-75 years were identified who underwent thyroidectomy. Patients were classified as either being treated or not treated with RAI, based on RAI data post-thyroidectomy. Patients were followed up for two to five years depending on their date of diagnosis from 2016 to 2020, using thyroglobulin (Tg), anti-thyroglobulin (anti-Tg), and thyrotropin (TSH) levels and ultrasound neck. Association between patients who received RAI and who did not receive RAI was determined and a p-value <0.05 was considered as statistical significance.

Results: Patients had mean age of 34.5 ± 10.4 years with majority of females (75.4%). Majority of the patients (94.6%) had total thyroidectomy with no neck dissection (83.1%). RAI therapy was conducted among 70.8% participants, of which, 56.9% participants received a dose of 100 mci. Most of the patients had positive outcomes as there was no recurrence among 96.2% participants. There was a significant difference in RAI therapy with total thyroidectomy as compared to subtotal, RAI dose, tumour stage, neck dissection, and lymph node involvement (p ≤0.001).

Conclusion: After complete tumour resection, a highly selected group of patients with low-risk local disease have shown low rate of recurrence when managed without RAI. Interestingly, the disease recurrence was also only seen in patients who received RAI therapy in comparison to those who did not receive RAI therapy.

Key words: Outcomes, Differentiated thyroid cancer, Radioactive iodine, Ablation therapy, Post-surgery.