“…However, secondary hepatobiliary tumors are more common and occur 2.5 times more frequently than primary ones (Collett,1998). In human medicine gallbladder polyps have been observed in 0.004 to 13.8 percent of resected gallbladders (Christensen, 1970;Stringer, 2003), and in 1.5 to 4.5 percent of gallbladders assessed by ultrasonography (Jorgensen, 1990;Veronica, 2006). In one report, no association was observed between the presence of polyps and the patient's age, sex, weight, number of pregnancies, use of exogenous female hormones, or any other risk factors that are generally believed to be associated with gallstones (Stringer, 2003).…”