Gallbladder cancer stage I: Cancerous tissue is limited to the mucosa, i.e. carcinoma in situ. Stage II: Invasion to the muscular layer. Stage III: Cancer invades the whole layer of gallbladder wall. Stage IV: Invasion of the whole layer of gallbladder wall and metastasis of surrounding lymph nodes. Stage V: direct invasion of liver or metastasis to other organs or distant metastasis.