Studies on surgical operations and prognosis of extrahepatic bile duct cancer

Table 2 Mean survival period of the total 55 patients with extrahepatic bile duct cancer according to treatment

Group	Treatment	n	Mean survival period (¯x ± s, mo)
1	tumor curative resection	11	21.4 ± 16.7b
2	biliary-enteric bypass	14	12.2 ± 6.8a
3	operative stent insertion	16	7.4 ± 3.4
4	permanent PTCD	6	4.3 ± 1.5
5	conservative treatment or exploratory laparotomy only	8	2.3 ± 1.8

^bP < 0.01 vs groups 2-5;

^aP < 0.05 vs groups 3-5. PTCD: Percutaneous transhepatic cholangio-drainage.