Metastasis

Carcinoma

Thyroid carcinoma

Lymphovascular invasion

Lymph node

Meta-analysis

Internal medicine

Oncology

Medicine

Gastroenterology

Lymph node metastasis

Cancer

Thyroid

International Journal of Surgery

Lymph node metastasis (LNM) is frequent in papillary thyroid carcinoma (PTC) and is associated with a poor prognosis. Unlike central LNM (CLNM), there are few studies focusing on LLNM. We aimed to investigate the prevalence and the risk factors for LLNM, with its most prevalent sites. We performed a comprehensive literature search using the PubMed and EMBASE databases for relevant studies published prior to November 2016 that examined the risk factors for LLNM. Twenty-three studies, including 18,741 patients, were included. The prevalence of LLNM was 20.9% in all patients. CLNM (pooled OR = 7.84, 95% CI = 6.13–10.02, p < .0001), extrathyroidal extension (pooled OR = 3.22, 95% CI = 2.21–4.70, p < .0001), tumor multifocality (pooled OR = 2.19, 95% CI = 1.67–2.89, p < .0001), male sex (pooled OR = 1.72, 95% CI = 1.50–1.98, p < .0001), upper pole location (pooled OR = 2.96, 95% CI = 1.93–4.53, p < .0001), tumor size ≥1.0 cm (pooled OR = 2.49, 95% CI = 1.71–3.61, p < .0001), lymphovascular invasion (pooled OR = 3.96, 95% CI = 2.61–6.03, p < .0001) and tumor bilaterality (pooled OR = 1.31, 95% CI = 1.12–1.53, p = .0006) were significantly associated with LLNM. Most frequently affected areas were levels III and IV. The prevalence of LLNM was high although the prognostic impact is unknown. The significant risk factors for LLNM were not much different from known risk factors for CLNM.

Lateral lymph node metastasis in papillary thyroid carcinoma: A systematic review and meta-analysis for prevalence, risk factors, and location