Prediction of Thyroid Malignancies by Thyroid Auto Antibodies

Thyroid cancer is the most frequent cancer among endocrine tumors, and account for approximately 1% of all malignancies. Recent literature has suggested an association between autoimmune thyroiditis and papillary thyroid cancer. The aim of the study was to choose the role of preoperative thyroid auto-antibodies as a predictive marker that could distinguish benign and malignant thyroid nodules and any other occult malignancy. This cross sectional study was done from July 2012 to June 2014 in department of Surgery Sir Salimullah Medical College & Mitford Hospital (SSMC&H) in collaboration with department of Otolaryngology SSMC&H, Bangabandhu Sheikh Mujib Medical University, Dhaka Medical College and Bangladesh Medical College of Dhaka city. Inclusion criteria were all patients presenting with thyroid swelling. For this study, 116 patients of thyroid swelling were studied by detailed history, clinical examination, thyroid hormone assay (serum T₃, T₄, TSH), ultrasonogram to detect single or multiple nodules, solid or cystic condition of nodules, thyroid scan to see functional status of gland, FNAC to detect benign or malignant condition preoperatively, thyroid auto antibodies (Tg-Ab and TPO-Ab) and histopathological examinations. FNAC outcomes were compared with anti-thyroid auto antibodies (ATA) and histopathological reports. In this study it showed that out off 89 benign classes 53 were with raised and 36 were with normal anti-thyroid auto anti-bodies (Tg-Ab+TPO-Ab). Among the raised 53 patient only 14(26.41%) were proved malignant in histopathological examination. On the other hand out off 36 normal anti-thyroid auto anti-bodies (Tg-Ab+TPO-Ab), 5(13.88%) became malignant histopathologically. In the cytological malignant group out off 17 patient 8 (47.05%) were with normal anti-thyroid auto anti-bodies (Tg-Ab+TPO-Ab) and 09(52.95%) were with raised anti-thyroid auto anti-bodies (Tg-Ab+TPO-Ab) and all of them were histologically malignant. It was observed that FNAC with high level of anti-thyroid auto anti-bodies (Tg-Ab+TPO-Ab) will be suspicious for malignancy but not statistically significant in this study odds ratio for anti-thyroid auto anti-bodies (Tg-Ab+TPO-Ab) within normal and raised were 0.78(0.501-1.214) and 1.23(0.807-1.89) respectively. In the series sensitivity, specificity, positive predictive value and negative predictive value of thyroid auto antibodies and FNACs were done by the ROC curve. It showed that PPV was highest 96% for FNAC and for Tg-Ab and TPO-Ab it was 27% and 24% respectively. In this study thyroid auto-antibodies were raised in both benign and malignant conditions. TPO-Ab was more raised than Tg-Ab in our country with malignant conditions of thyroid. Thyroid auto anti-bodies could not predict the malignant condition of thyroid. In our study the benign cytology with raised antithyroid auto antibodies showed risk to be malignant outcome in histopathology.