Delesi 30 pb gen laten membran protein-1 (LMP1) virus Epstein-Barr (EBV) pada penderita karsinoma nasofaring (KNF) di Indonesia = The 30-bp Deletion of Epstein-Barr Virus (EBV) latent membrane protein-1 (LMP1) gene in Indonesia Nasophatyngeal Carcinoma (NPC) patient