In vitro evidence of heterogeneity within pancreatic cancer.

The relative importance of the genome and environmental factors has not been established in pancreatic carcinogenesis. The identification of in vitro expressions of cancer genes should enhance such clarification. Hyperdiploidy, with the exception of a low incidence (0%-7%) of tetraploidy, has rarely been observed in dermal monolayer cultures from normal individuals without a family history of solid tumors. Hyperdiploidy (incidence over 1% in a culture) was not observed in dermal fibroblast monolayer cultures derived from 143 clinical normals (ages 18-80 years). In vitro hyperdiploidy (7%-14%), with a normal occurrence of tetraploidy (0%-3%), was observed in 6 of 28 patients with acinar adenocarcinoma of the body of the pancreas. No in vitro hyperdiploidy was observed in the remaining pancreatic cancer patients or in the 25 spouses with negative family cancer histories studied. As hyperdiploidy with a normal occurrence of tetraploidy has been previously reported [1] in a familial pancreatic cancer cluster, this chromosomal alteration was considered to be an in vitro expression of genetic predisposition for pancreatic cancer in approximately 20% of this small (28 patients) sample. In vitro studies on a significantly larger patient sample will be required to determine its incidence in a patient group with acinar adenocarcinoma of the body of the pancreas.