RB1 and embryonal carcinoma: In our study, LOH of the RB1 gene was found in nonseminomas with an embryonal carcinoma component, and both nonseminomas with LOH of RB1 also demonstrated LOH of the TP53 gene.21 Interestingly, the amount of embryonal carcinoma component in TGCT, along with vascular invasion, has been proved so far to be the only clinically valid prognostic factor for the development of stage II metastatic testicular cancer.26