PIK3R1 and cancer: Being the third most common cause of cancer death worldwide with the mortality rate of 8.2%, hepatocellular cancer (HCC) is a distinct tumor of the digestive system and exhibits a different genetic alteration pattern of PI3K/AKT pathway, such as PIK3CA (3%), PIK3R1 (1.2%), PIK3R2 (1.5%), AKT1 (0.7%), AKT2 (1.1%) and PTEN (4%) respectively (Table 1).