Background. Gallbladder cancer has an unusual geographic and demographic distribution, suggesting many possible etiologies. Methods. A case‐control study was undertaken at four hospitals in La Paz, Bolivia, and at one hospital in Mexico City, Mexico. Eighty‐four patients with newly diagnosed, histologically confirmed gallbladder cancer were compared with 126 control subjects without stones and with 264 control subjects with cholelithiasis or choledocholithiasis without cancer. All study subjects underwent abdominal surgery. Study subjects were interviewed regarding demographic characteristics, medical history, family history, diet, and exposure to agents presumed to be risk factors for biliary cancer. Results. Virtually all subjects in Mexico were judged to be mestizos (i.e., persons of mixed ancestry). In contrast, race was a very strong risk factor for gallbladder cancer in Bolivia. Relative to mestizos who spoke neither language, the odds ratio (95% confidence interval [CI]) for cases versus control subjects without stones for those 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 also noted for elevated maximum body mass index (P = 0.03), family history 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 also seen with elevated maximum body mass index; compared with those with a body mass index less than 24 kg/m2, those with an index of 24–25 kg/m2, 26–28 kg/m2, and greater than 28 kg/m2 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), respectively (asymptotic test for trend, P = 0.03). Finally, a number of associations were noted with certain dietary and cooking habits. Conclusions. Patients with gallbladder cancer differed from control subjects in race, body mass, physician‐diagnosed typhoid, and certain dietary patterns. These findings may provide useful clues to the pathogenesis of gallbladder cancer, but given the number of analyses performed, additional cases need to be studied. Cancer 1995:76:1747–56.

Conjunctival myxomas are uncommon tumours. For accurate diagnosis, histopathological examination is mandatory. The treatment of choice is surgical removal, and the prognosis is excellent.

In order to detect regions of DNA containing tumor suppressor genes involved in the development of gastric cancer, we performed an allelotype study on 78 gastric adenocarcinomas from a population composed largely of Texan Hispanics and Anglos, two ethnic groups that have a ratio of incidence rates of gastric cancer of approximately 2:1. In total, 42 microsatellite markers were employed, which detected at least one site per arm of each autosome in the human genome. These included several markers linked to known tumor suppressor genes (TP53, APC, DCC, RB1, and BRCA1). Sites showing quantitative allelic imbalance (AI) greater than 30% were located on 3p (36%), 11q (31%), 12q (38%), 13q (33%), 17p near TP53 (74%), and 17q near BRCAI (32%). Among the 22% of cases showing microsatellite instability (MI), a subset (4 of 17) showed instability at 59% or more of sites tested. No ethnic bias was detected in cases showing MI or in cases with AI at sites with rates of AI above 30%. Tumors of the intestinal subtype were significantly more likely than diffuse tumors to show AI at DI3S170 (P = 0.01). A deletion map of chromosome arm 3p was prepared for tumors with AI at D3S1478. These data indicate that a tumor suppressor gene on chromosome arm 3p is involved in the development of a subset of gastric cancers.

The poor prognosis of gallbladder cancer and the presence of high-risk populations make the identification of a screening test for this disease very desirable. As part of an ongoing case-control study of gallbladder cancer being conducted in Mexico City, Mexico, and in La Paz, Bolivia, blood specimens were sought from all patients with cancer of the gallbladder and on controls of similar age and sex undergoing upper abdominal surgery. Each sample was analyzed for carcino-embryonic antigen (CEA) and CA 19-9. Using the specimens from Bolivia, a serum CEA cutoff of 4.0 ng/ml yielded a sensitivity of 50.0% and a specificity of 92.7%, while a serum CA 19-9 cutoff of 20.0 units/ml yielded a sensitivity of 79.4% and a specificity of 79.2%. Using ROC curve analysis, the latter was a much better test than the former (p less than 0.05). Using the tests in series or in parallel did not substantively improve the results. The specimens from Mexico were used for validation purposes, and yielded very similar results. In conclusion, serum CA 19-9 and CEA are fairly good tests for discriminating patients with gallbladder cancer from patients with gallstones and no cancer, the former being a better test than the latter. These tests may be useful in identifying disease recurrences. In addition, if a sufficiently high-risk population could be identified, this could potentially become a useful screening test for this serious disease, allowing early intervention. However, additional data are needed prior to recommending this clinically.

Gastric cancer is more than twice as common in Hispanics as in Anglos in Texas, while colorectal cancer is almost twice as common in Anglos as Hispanics. To test the hypothesis that mutations in the p53 tumour suppressor gene are involved in these differences, we examined 131 gastric and 138 colorectal cancers from Hispanic and Anglo patients from South Texas and Mexico using immunohistochemistry (IHC) as a screening assay for p53 mutations. The fraction of p53 positive cases was not significantly different in gastric cancers from Hispanics compared to Anglos (43% versus 61%, respectively, p = 0.13) or in colorectal cancer (57% versus 58%, respectively, p = 1.0), suggesting that p53 mutations are not involved in causing the different incidences of these cancers in these populations. In addition, the types of p53 mutations arising in gastric tumours from Hispanic patients were consistent with those reported in gastric tumours in other populations. Sequencing of mutations in five gastric cancers revealed two G:C to A:T transitions, two A:T to G:C transitions and one complex deletion. In contrast with findings in studies in other tumour types, neither stage nor survival was associated with p53 positive staining by IHC in either gastric or colorectal tumours in this study. Positive p53 immunostaining was associated with the diffuse histological subtype in gastric carcinoma (p = 0.05) and high histological grade in colorectal carcinoma (p = 0.04).