Predictive factors for node involvement in papillary thyroid carcinoma. Univariate and multivariate analyses.

For patients with papillary thyroid carcinoma, lymph node involvement is a common complication, resulting in node dissection and its resulting morbidity. To determine means of limiting lymph node dissections, we attempted to define intra-operative criteria predictive of node metastasis and so identify the patients likely to benefit from this procedure. This retrospective study concerned 158 patients (118 female) treated between 1974 and 1996 for papillary thyroid carcinoma by total thyroidectomy associated with bilateral (central and lateral) (n = 119) or unilateral (n = 39) dissection. The following criteria were used to study the predictive value of node involvement: age, sex, tumour size, tumour site, uni- or multifocality, existence or not of a tumour capsule, existence or not of perithyroid involvement and presence or not of vascular invasion. 99 patients (63%) had node involvement. Four factors showed predictive value for node involvement in univariate analysis: vascular invasion (P = 0.02), male sex (P = 0.008), absence of a tumour capsule (P < 0.0001) and perithyroid involvement (P < 0.0001). Two factors were predictive in multivariate analysis: absence of a tumour capsule and perithyroid involvement. Our results enabled us to calculate the risk of node involvement for each patient as a function of the existence of a peritumoral capsule and/or perithyroid involvement and to determine the indication for dissection. When neither of these factors was present, the risk of node involvement was 38.3% and dissection was not considered essential. If both risk factors were found, the risk was 87.1% and dissection was considered necessary.