Demographic and Prognostic Significance of Surgically-Treated Intrathyroidal Thymic Carcinoma: A Systematic Review and Meta-Analysis.

Abstract

To synthesize evidence on the demographic and prognostic profile of surgically treated intrathyroidal thymic carcinoma (ITC). A PRISMA-compliant systematic review and meta-analysis was conducted. Due to the rarity of the disease, all patients with surgically treated ITC were combined from individual case reports to create a cohort of patients which was subsequently pooled with other eligible case series. Single-arm meta-analysis was used to synthesize a demographic profile and Kaplan-Meier statistics were used for survival analyses. Analysis of 55 articles (154 patients) showed that patients with ITC are likely to be symptomatic (95.2%, 95% CI 91.1-99.2) with neck mass (72.2%, 62.2-82.1) as the most common symptom with no laterality preferences (left:right, 46.4%:53.6%). Overall survival (OS) at 15 years was 96.0% (mean OS time:19.7 years; median OS time 18 years). Recurrence-free survival (RFS) at 15 years was 77.9% (mean RFS time:13.4 years; median RFS time: 17 years). RFS was not affected by symptomatic status (HR: 0.0001, p = 0.96), tumor size (HR; 1.044, p = 0.113), lymph node metastasis (HR: 1.909, p = 0.307), extrathyroidal extension (HR: 0.769, tumor p = 0.688), surgery plus radiotherapy (HR: 0.434, p = 0.207), surgery plus chemoradiotherapy (HR: 0.0001, p = 0.959), subtotal thyroidectomy (HR: 0.821, p = 0.854), lobectomy (HR: 0.366, p = 0.140), lymph node dissection (HR: 1.088, p = 0.888). Surgically treated ITC may have excellent long-term prognosis which seems to be not affected by the extent of resection or use of adjuvant therapy; however, this could be type 2 error; hence more robust evidence is required for definitive conclusions.