Chronic lymphocytic thyroiditis does not influence the risk of recurrence in patients with papillary thyroid carcinoma and excellent response to initial therapy.

Background: This study evaluated the recurrence in patients with papillary thyroid cancer and an excellent response to initial therapy, comparing those with and without chronic lymphocytic thyroiditis.

Methods: This was a prospective study. Patients who met the following criteria were selected: diagnosis of papillary thyroid cancer; submitted to total thyroidectomy followed or not by ablation with I; and neck ultrasonography without abnormalities, nonstimulated thyroglobulina (Tg) ≤0.2 ng/ml, and undetectable antithyroglobulin antibodies (TgAb) 12-18 months after initial therapy. The patients were divided into two groups: group A, with chronic lymphocytic thyroiditis on histology; group B, without chronic lymphocytic thyroiditis on histology.

Results: Groups A and B were similar in terms of sex and age of the patients, characteristics of the tumor, tumor-node-metastase stage and risk category. The time of follow-up ranged from 24 to 120 months (median 66 months). During follow-up, 5 patients of group A (2.6 %) and 9 patients of group B (2 %) developed recurrence (p = 0.77). Patients with chronic lymphocytic thyroiditis were more likely to progress to persistently borderline TgAb. No patient had positive TgAb (above the reference value) during follow-up. Recurrences occurred in 12/588 patients (2 %) with undetectable TgAb in all measurements, in 1/32 (3.1 %) with detectable TgAb on some occasion but that returned to undetectable spontaneously, and in 1/13 (7.7 %) with persistently borderline TgAb. These rates did not differ significantly (p = 0.25).

Conclusion: The results of the present study showed the absence of an association between chronic lymphocytic thyroiditis and recurrence risk at least in patients with an excellent response to initial therapy.