The purpose of this study was to investigate the clinical significance of DNA ploidy, as assessed by flow cytometry, for pancreatic and peripancreatic cancers. Between 1988 and 1990, we examined fresh/frozen samples from 49 patients who had histologically confirmed adenocarcinomas of the bilio-pancreatic carrefour: They had 23 cancers of the pancreas, 21 of the Vater's papilla, and 5 of the common bile duct. All patients were selected among a cohort of subjects who underwent Endoscopic Retrograde Cholangio Pancreatography (ERCP) and/or surgery. No prognostic impact of age, sex, stage, and surgical treatment on survival was observed by univariate analysis. When the affected organ was considered, a statistically significant difference in survival was observed: At 88 wk, survival was 0% for pancreatic and common bile duct cancer patients, and 18.2% at 175 wk for Vater's papilla cancer patients (p = 0.04). In addition, we found, irrespective of affected organ, that the patients with DNA diploid tumors had a statistically significant survival advantage as compared to those with DNA aneuploidy (p = 0.02). Furthermore, the statistically significant prognostic power of DNA ploidy was confirmed when patients with tumors of the pancreas and those with tumors of the Vater's papilla were separately analyzed.(ABSTRACT TRUNCATED AT 250 WORDS)