RISK-FACTORS FOR GALLBLADDER CANCER - AN INTERNATIONAL COLLABORATIVE CASE - CONTROL STUDY

Background. Gallbladder cancer has an unusual geographic and demograph ic distribution, suggesting many possible etiologies. Methods. A case- control study was undertaken at four hospitals in La Pat, Bolivia, and at one hospital in Mexico City, Mexico. Eighty-four patients with new ly diagnosed, histologically confirmed gallbladder cancer were compare d with 126 control subjects without stones and with 264 control subjec ts with cholelithiasis or choledocholithiasis without cancer, All stud y subjects underwent abdominal surgery. Study subjects were interviewe d regarding demographic characteristics, medical history, family histo ry, diet, and exposure to agents presumed to be risk factors for bilia ry cancer. Results. Virtually all subjects in Mexico were judged to be mestizos (i.e., persons of mixed ancestry). In contrast, race was a v ery strong risk factor for gallbladder cancer in Bolivia. Relative to mestizos who spoke neither language, the odds ratio (95% confidence in terval [CI]) for cases versus control subjects without stones for thos e who spoke Aymara well was 15.9 (CI, 1.9-179), whereas it was 1.4 (CI , 0.2-8.2) for those who spoke Quechua well. An increased risk was als o noted for elevated maximum body mass index (P = 0.03), family histor y of gallstones (odds ratio [OR] = 3.6 [CI, 1.3-11.4]), and physician- diagnosed typhoid (OR = 12.7 [CI, 1.5-598]). An increased risk was als o seen with elevated maximum body mass index; compared with those with a body mass index less than 24 kg/m(2), those with an index of 24-25 kg/m(2), 26-28 kg/m(2), and greater than 28 kg/m(2) had odds ratios of 1.6 (CI, 0.4-7.6), 1.3 (CI, 0.3-5.6), and 2.6 (CI, 0.5-18.6), respect ively (asymptotic test for trend, P = 0.03). Finally, a number of asso ciations were noted with certain dietary and cooking habits. Conclusio ns. Patients with gallbladder cancer differed from control subjects in race, body mass, physician-diagnosed typhoid, and certain dietary pat terns. These findings may provide useful clues to the pathogenesis of gallbladder cancer, but given the number of analyses performed, additi onal cases need to be studied.