Impact of solitary thyroid nodule size on probability of thyroid malignancy

Background Tumor size is considered an important predictor of malignancy in many types of cancer. However, there is no clear line of characterization regarding the association between thyroid nodule size and prediction of malignancy risk. Current data continue to be variable between different studies. Aim To determine the impact of solitary thyroid gland nodule size as an independent factor on increasing the probability of malignancy. Patients and methods Our study was held as a prospective study conducted on 60 patients having a solitary thyroid nodule undergoing either total thyroidectomy or lobectomy, the 60 patients were divided into three nodule-size groups: group A: 1.5-3.5cm (20 patients), group B: 3.6-5.5cm (20 patients), and group C: any nodule larger than 5.5 cm (20 patients). Results In this study, 60 patients with solitary thyroid nodule were subdivided into equal nodule-size groups: group A:1.5-3.5cm (20 patients), group B: 3.6-5.5cm (20 patients), and group C: any nodule larger than 5.5cm (20 patients), nine (15.0%) patients out of a total of 60 patients turned to be malignant by final histopathology, two (10.0%) from group A, six (30%) from group B, and one (5.0%) from group C. The result is that there is no increased probability of malignancy associated with increasing thyroid size with relative increase of probability of malignancy in group B. Conclusion Large solitary thyroid nodules are not associated with an increased probability of malignant disease beyond that which is expected based on their cytological classification. Furthermore, our data would suggest that thyroid nodule sizes ranging between 3.5 and 5.5 cm, as opposed to larger ones, pose a relatively increased risk of malignant disease.