Thyroid autoimmunity increases the risk of thyroid cancer in patients with thyroid nodules: recent confirmations form a prospective study.

OBJECTIVE: The association between autoimmune thyroid diseases (AITD) and papillary thyroid carcinoma (PTC) is still controversial and it is based only on retrospective analyses. Aim of this study was to evaluate this association in a prospective study of unselected consecutive thyroid nodules (TN) submitted to fine-needle aspiration cytology (FNAC). In all series, serum concentrations of anti-thyroperoxidase, TPOAb and anti-thyroglobulin, TgAb (ATA) and TSH were measured before FNAC; histological analyses were performed in all surgical samples. SUBJECTS AND METHODS: 196 patients (252 nodules) with TN were studied. 106 patients (142 TN) had undetectable ATA (ATA-), while 90 (110 TN) were ATA positive (ATA+), including 78 (93 TN) with AITD with hyper or hypothyroidism and/or thyroid hypoechogenicity on ultrasound. Cytology was classified as benign (TIR 2), indeterminate (TIR 3), suspect and malignant (TIR 4-5). Of 61 patients (75 TN) submitted to surgery, histological diagnosis and lymphocytic thyroid infiltration (LTI) description were available. RESULTS: A significantly higher prevalence of classes TIR 4-5 (20% vs 9.8%, p<0.05) and lower prevalence of class TIR 2 (59.1% vs 63.4%, p<0.05) were found in ATA+ vs ATA- nodules, respectively. These differences were even more evident when only TN with coexistent AITD were compared to ATA- group (TIR 4-5, 22.6% vs 9.8%, p<0.01; TIR 2, 53.8% vs 63.4%, p<0.01). A significant association (p=0.002) between TgAb+ TN and TIR 4-5 classes vs TgAb- TN with an association trend of borderline significance (p=0.6) for TPOAb were found. A progressive increase of TSH levels in TIR 4-5 vs TIR 2 classes was also observed. Histological analysis confirmed a significantly increased prevalence of PTC, (68.8% vs 44.2%, p<0.05) in AITD vs ATA– group, while a higher prevalence of LTI was also observed in malignant vs benign nodules (66% vs 34%, p