In 22 initial germinoma cases, CD3+ TIL density was significantly higher among patients with high expression of PD-1 than in those with low expression of PD-1 (4008 ± 376.3/mm2 versus 2212 ± 523.6/mm2, t = 2.785, P = 0.018) (Fig 3A and 3B). Here, PDCD1 is linked to germinoma.