Malignancy of a thyroid nodule is more likely when the formation is spherical. In the future, it may be possible to include nodule shape in a cancer risk stratification system.
Scientists at the Dana-Farber Cancer Institute have found that the shape of a thyroid nodule can predict the risk of developing cancer. With a spherical shape of the node, as evidenced by the ratio of the long and short parts, the risk of malignancy is higher. The study results were published in The Journal of Clinical Endocrinology & Metabolism.
The revealed pattern does not depend on age, gender and size of the node. The study included patients with one or two clinically significant thyroid nodules (mostly solid and more than 1 cm) presenting for diagnostic evaluation. Ultrasound of the thyroid gland, cytological examination with fine-needle biopsy and/or histopathological examination in the case of thyroid surgery were performed. Scientists looked at the ratio of the lengths of the node and its relationship with data on the benignity or malignancy of the process, confirmed by biopsy.
The ratio of the node’s side parameters (long to short) was significantly lower in malignant tumors compared to benign ones. This indicates a greater risk of malignancy in spherical nodules (1.63 ± 0.38 for malignant nodules vs. 1.74 ± 0.47 for benign ones). The more spherical the nodule was, the aspect ratio approaching 1.0, the higher the risk of malignancy.
In multiple regression analysis, younger age, male gender, and spherical nodule shape were independently associated with cancer risk.
Predictive risk models for thyroid nodule cancer are based on nodule composition, echogenicity, margins, and the presence of microcalcifications. Nodule shape has shown promise as an additional factor that may improve risk stratification and individualized clinical decision making.