Abstract
BACKGROUND: Tumor diameter may not reflect tumor burden accurately in all cancers. In this study, we aimed to investigate the relationship between tumor volume (TV) and aggressive features and prognosis in papillary thyroid cancer (PTC). METHODS: Patients diagnosed with single foci PTC were recruited for the study. The largest tumor diameter was considered as the primary tumor diameter. TV was calculated using the formula for an ellipsoid shape, considering the three pathologically specified dimensions. Primary tumor diameter and TV were compared in terms of aggressive tumor characteristics and prognosis. RESULTS: The data of 118 patients were analyzed. There was no significant relationship between primary tumor diameter and lymph node metastasis (LNM), extrathyroidal extension (ETE), and vascular invasion (p > 0.05 for each). In patients with tumor diameter >2 cm, TV was negatively associated with LNM (p = 0.015). One-unit increase in TV was associated with 1.629 times greater likelihood of absence of LNM (95% CI: 1.099-2.415). When the TV was ≤5.26 cm(3), the sensitivity and specificity for the presence of LNM were 88.9% and 75.8%, respectively. Again in this group, the sensitivity for the occurrence of ETE was 100.0% and specificity was 45.7% when the TV was ≤9.49 cm(3). There was no significant difference in the five-year disease-free survival between tumor diameter and TV. CONCLUSIONS: In contrary to studies with other cancer types in the literature, there was a significant but negative relationship between TV and LNM. Further large-scale studies are needed to determine whether TV can be used as a prognostic factor in PTC.