Influence of lymphocitic thyroiditis on prognostic outcome differentiated thyroid carcinoma

Backgraund/aim. Thyroid carcinoma is rare malignant tumors. They are typically presented with slow progression and clinical course. Lymphocytic infiltration, including fagocytosis of neoplastic cells by macrophage plays an important role in preventing development of distant metastases. This paper sets the following objectives: Establish whether presence or absence of Hashimoto thyroiditis in differentiated thyroid carcinoma (DTC) is a favourable prognostic factor. Methods. The group under examination here are all newly diagnosed patients with differentiated thyroid carcinoma surgically treated at the Surgery Clinic in Podgorica from 2003. to 2010. A total of 125 patients, aged 11 to 79, were included in this research. The patients were divided in two groups, those with and those without lymphocytic infiltration. Both groups were mutually compared for their prognostic factors. For the identification of T and B lymphocytes, anti-CD 3 and anti-CD 20 antibodies were used. Student t-test was used for comparison of clinical and pathological parameters among groups, Hi square test for comparison of frequency, and Coxs regression model for time dependant variables as frequency of recurrence among groups with various stages of disease. Survival curve (Kaplan-Meier) is used for comparison of time dependant variables (survival, recurrence, death). The follow-up time ranges from 10 to 70 months in both groups of patients. Results are as follows: presence of lymphocytic infiltration in thyroid tissue in patients with differentiated thyroid carcinoma is significant prognostic factor (P<0.0001). But, absence of lymphocytic infiltration is a poor prognostic factor in patients with invasive extra thyroid tumours (P<0.0001). Also, absence of lymphocytic infiltration is a poor prognostic factor for development of lymphogenic and hematogenic metastases. The presence of T or B lymphocytes and varying degree of their presence is not a significant prognostic factor (P<0.0046). Patients without lymphocytic infiltration are significantly more numerous in the fourth stage of disease (P<0.0001). There is no statistically significant difference in terms of the presence of T or B lymphocytes in the tissue. Chronic lymphocytic thyroidis hahshimoto is a favourable prognostic factor in our examined group (P<0.0001). Local invasiveness and extrathyroid expansion is significantly smaller in the group of patients with the presence of lymphocytic infiltration (P<0.0001). By means of univariate analysis, we found that factors with a significant impact on survival rate include age (P<0.0001), size of tumour (P<0.018), extrathyroid invasiveness (P<0.0001), hematogenic metastases (P<0.049). Lymphocytic infiltration is present in 81% of patients in their thyroid gland, and in 19% patients there are no lymphocytes in tissue. Limphocitic infiltration has a favourable influence on tumor variables. Conclusion.This research has shown that lymphocytes in tissue as part of Hashimoto thzroiditis have an effect on certain prognostic factors of differentiated thyroid carcinoma as size, smaller invasiveness and extrathyroid tumour growth and incidence of hematogenic metastases.