Results of Radioactive Iodine (131I) Therapy in Well Differentiated Thyroid Carcinoma: A Retrospective Study from the Tygerberg Hospital

Introduction: Well Differentiated thyroid carcinoma (WDTC) represents 80% of all thyroid malignant tumours, with good prognosis and a survival rate higher than 90% at 20 yrs. Total or subtotal thyroidectomy is the treatment of choice, with radioactive iodine (RAI) therapy reserved for adjuvant setting/ablation and/or as a curative treatment modality in patients with local recurrence and/or distant metastases. This retrospective study aimed to investigate the treatment outcome, survival rate and prognostic factors in our institution over the past half-decade.

Methods: A retrospective study was conducted of 33 patients with WDTC. Data were collected from 1stJanuary 2007 to 31st December 2012 and included: Age at diagnosis, sex, histology, TNM stage, treatment received, indication for 131I therapy, doses of 131I, complication of treatment, follow-up diagnostic scan 123I / Thyroglobulin, time of recurrence since surgery and cause of death. Prognostic factors were analysed using chi-square test and crude mortality rate was used.

Results: Papillary subtype is the most common type of WDTC (63.6%); mean age at diagnosis is 50 years and female to male ratio is cosmopolitan at 3.1:1 with female preponderance. RAI therapy after thyroidectomy (total or subtotal) offers complete remission in 26/33 (78.8%) and the overall mortality rate was 3/33 (9.1%) p=0.023.

Conclusion: RAI therapy is safe and effective in management of patients with WDTC. The initial surgical approach is the cornerstone in the subsequent outcome of RAI therapy with very poor outcome registered in unresectable thyroid tumour and in patients with multiple organ metastases.