Noninferior response in BRAF^V600E mutant nonmetastatic papillary thyroid carcinoma to radioiodine therapy

As the most frequent and specific genetic alteration in papillary thyroid carcinoma (PTC), BRAF^V600E has an intimate relationship with more invasive tumour and higher postoperative recurrence risk in PTC patients. We investigate the effect of radioactive iodine (RAI) therapy on the clinical outcome in PTC patients with the BRAF^V600E mutation without distant metastases.

This retrospective study included PTC 228 patients without distant metastases who underwent total or near-total thyroidectomy and RAI treatment in our hospital from January 2011 to July 2014. The BRAF^V600E status of the primary lesions was determined and the patients were divided into two groups according to the presence of the mutation. Serological and imaging data were collected at a median follow-up of 2.34 years after RAI administration. Suppressed and stimulated thyroglobulin (Tg), Tg antibody, diagnostic whole-body scintigraphy, and other imaging examinations were used to assess clinical outcome, which was defined as excellent response, indeterminate response, biochemical incomplete response and structural incomplete response.

The BRAF^V600E mutation was observed in 153 of the 228 patients (67.1 %). The clinicopathological features did not differ between the BRAF^V600E mutatation and wild-type groups except age at diagnosis (P = 0.000), tumour size (P = 0.023) and TNM stage (P = 0.003). Older age and more advanced TNM stage were prevalent in the BRAF^V600E mutatation group, whereas tumours were slightly larger in the BRAF^V600E wild-type group. The response to RAI therapy was evaluated in both the entire series and the patients with a high recurrence risk, and no significant difference in response was found between the BRAF^V600E mutatation and the wild-type groups (P = 0.881 and P = 0.851, respectively).

The clinical response to timely postsurgical RAI therapy is not inferior in BRAF^V600E mutation PTC patients without distant metastases, which suggests that RAI therapy might improve the general clinical outcome in this patient group.