Tumour Size and Bilateral Thyroid Cancer after Thyroidectomy

Abstract

Objective 1) Determine the incidence of bilateral papillary thyroid cancer (PTC) after total thyroidectomy (TT). 2) Compare tumour size, demographic and prognostic factors between bilaterality and non-bilaterality (unilateral and/or isthmian involvement). Methods Pathology reports of 491 patients who underwent TT between 2002 and 2007 and had a definite diagnosis of PTC were reviewed. Statistical significance was obtained using chi-square analysis. Results 66 patients (13.4%) had bilateral PTC, of whom 4 also had isthmian involvement; 26 (5.3%) had PTC in the isthmus only; and 399 (81.3%) had unilateral PTC, of whom 15 also had isthmian involvement. Bilaterality was present in 12.1% of women and 19.5% of men; and in 14.9% of patients aged below 45 and 12.4% of patients aged 45 and above (all p-values non-significant). Among bilateral PTC patients, 69.7% had a primary tumour greater than 2 cm, 48.5% had extracapsular extension, and 37.8% had lymph node (LN) metastasis; as compared to 66.1%, 21.9%, and 16.1%, respectively, in non-bilateral PTC patients (p-values non-significant, <0.001, and <0.01). Incidence of bilaterality was 25.8% and 23.7% in presence of extracapsular extension and LN metastasis, correspondingly; as opposed to 9.4% and 8.9% in their absence. Conclusions In our study, 13.4% of patients had bilateral PTC at TT. No significant correlation was established between bilaterality and gender, age, and tumour size. Bilateral PTC patients were more commonly found to have extracapsular extension and LN metastasis. Both these prognostic factors were associated with a higher incidence of bilaterality. These findings elucidate that bilateral involvement may constitute a poor prognostic indicator.