PLAC1 and neoplasm: PLAC1 is classified as a cancer/testis antigen (CTA) (39), with elevated expression reported in several tumor types, including stomach (40), colon (41), liver (42), pancreas (43), prostate (44), ovary (45, 46), uterus (47), cervix (48), breast (49), lung (37), HNSC (38, 50) and nasopharynx carcinoma (51).