Lymphovascular invasion and presence of embryonal carcinoma as risk factors for occult metastatic disease in clinical stage I nonseminomatous germ cell tumour: A systematic review and meta‐analysis

OBJECTIVE: To systematically review the literature on the prognostic value of lymphovascular invasion (LVI) and embryonal carcinoma (EC) for occult metastatic disease in clinical stage I nonseminomatous germ cell tumour (CS I NSGCT). MATERIALS AND METHODS: The PubMed, Embase (OVID) and SCOPUS databases were searched up to March 2019. Studies reporting on the association between LVI and/or EC and occult metastatic disease were considered for inclusion. The quality and risk of bias were evaluated by the Quality in Prognosis Studies tool. RESULTS: We screened 5287 abstracts and 207 full-text articles. We included 35 studies in the narrative synthesis and 24 studies in a meta-analysis. LVI showed the strongest effect. Pooled rates of occult metastasis were 47.5% and 16.9% for LVI-positive and LVI-negative patients, respectively (odds ratio [OR] 4.33, 95% confidence interval [CI] 3.55-5.30; P 50% and 20.0% for EC 50% have similar ORs for occult metastasis. This shows that the assessment of EC presence is sufficient for the classification of EC.