One-third of an Archivial Series of Papillary Thyroid Cancer (Years 2007-2015) Has Coexistent Chronic Lymphocytic Thyroiditis, Which Is Associated with a More Favorable Tumor-Node-Metastasis Staging

Abstract

The significance and impact of the coexistence of chronic lymphocytic thyroiditis (CLT) with thyroid cancer is still debated. To verify the influence of CLT on papillary thyroid cancer (PTC), we retrospectively collected 505 PTC cases and analyzed age at diagnosis, sex, size, lymph node status, and staging. We found that CLT was present in 168 PTC (33.3%). Compared with the 337 patients without CLT (non-CLT), CLT patients were younger (44.42 ± 13.72 vs. 47.21 ± 13.76 years, P = 0.03), had smaller tumors (9.39 ± 6.10 vs. 12 ± 9.71 mm, P = 0.002), and lower rate of lymph node metastases (12.5 vs. 21.96%, P = 0.01, OR = 0.508). Tumor-node-metastasis (TNM) staging (T1a through T4) was more favorable for the CLT group compared to the non-CLT group (for instance, T1a = 65.5 vs. 49.8%, T3 = 4.8 vs. 23.4%). This study shows that one in three patients with PTC harbors CLT, which is associated with a more favorable TNM staging, consistently with a favorable outlook of PTC.

Keywords: autoimmune thyroiditis; autoimmunity; cancer; chronic lymphocytic thyroiditis; papillary thyroid cancer.

Figure 1

Age distribution of all 505 patients with papillary thyroid cancer (A) and the two groups with [n = 168 (B)] or without [n = 337 (C)] chronic lymphocytic thyroiditis.

Figure 2

Comparison between patients’ age according to sex and presence (black bars) or absence (white bars) of chronic lymphocytic thyroiditis (CLT). Only significant (P < 0.05) or borderline significant (P between 0.05 and 0.10) statistical differences are reported. Symbols: *P = 0.03; ^§P = 0.058; ^{^}P = 0.02.

Figure 3

Frequency of the seven variants of papillary thyroid cancer (A), and corresponding distribution of age (B–H).

Figure 3

Frequency of the seven variants of papillary thyroid cancer (A), and corresponding distribution of age (B–H).

Figure 4

Comparison between age of patients according to histotype and presence (black bars) or absence (white bars) of chronic lymphocytic thyroiditis (CLT). The striped bars represent all patients. Note that only the three most frequent histotypes are reported (see Figure 3A). Only significant (P < 0.05) and borderline significant (P between 0.05 and 0.10) statistical differences are reported. Symbols: *P = 0.03; ^§P = 0.03; ^{^}P = 0.004; P = 0.03; ^#P = 0.06.

Figure 5

Comparison between tumor size according to histotype and presence (black bars) or absence (white bars) of chronic lymphocytic thyroiditis (CLT). The striped bars represent all patients. Note that only the three most frequent histotypes are reported (see Figure 3A). Only significant (P < 0.05) statistical differences are reported. Symbols: *P = 0.002; ^§P = 0.008; ^{^}P = 0.009.