Insular carcinoma represents a more aggressive subtype of differentiated thyroid cancer on multivariate analysis after controlling for various clinicopathologic parameters.
Tertiary referral center at a university hospital.
One hundred twenty-seven consecutive patients having a histological diagnosis of the follicular variant of papillary thyroid carcinoma or follicular thyroid carcinoma.
Main Outcome Measure
A logistic regression model was used to examine the relationship between various clinicopathologic parameters and the insular subtype.
The insular subtype involved 14 of 127 tumors. Unlike extrathyroidal extension and nodal metastasis, primary tumor diameter (>40 mm vs ≤40 mm; P = .008) and distant metastasis (P = .003) correlated with the insular subtype. Both parameters were interrelated since tumors greater than 40 mm displayed distant metastasis more often (30% vs 8%; P = .008) than tumors measuring 40 mm or less.
These findings suggest that an unidentified somatic event may induce an accelerated proliferation of the transformed thyrocytes, which may ultimately result in enhanced rates of distant metastasis with increasing tumor volume.