GENETIC EPIDEMIOLOGY OF COLON-CANCER IN THE COTTON-TOP TAMARIN (SAGUINUS-OEDIPUS)

Colon cancer is known to be heritable in humans, but the opportunity t o investigate the genetic epidemiology of cancer in nonhuman primates has been limited by the size of available populations. The cotton-top tamarin (Saguinus oedipus) colony at the Oak Ridge Associated Universi ties (ORAU) Marmoset Research Center is a large population with a high rate of spontaneous colon cancer that has been monitored over several years, thus allowing investigation of the genetic basis for colon can cer in this colony. The presence of colon cancer at death was scored i n 392 necropsies at the colony. Genealogical and demographic data for these animals were obtained from colony records. The heritability of t he liability to colon cancer was estimated using maximum-likelihood-ba sed pedigree analyses after evaluating the effects of gender, origin ( wild-born or laboratory-born), and age at death on cancer experience. Cancer rates were not significantly different between males and female s or between wild- and laboratory-born animals. Differences in age at death were also statistically insignificant for both laboratory- and w ild-born animals. The heritability estimate for the liability to contr act colon cancer is 17% for the ORAU cotton-top tamarins. This heritab ility estimate is not significantly different from zero, indicating no evidence for heritable variation in cancer experience in this populat ion. If genetic factors affect cotton-top tamarin colon cancer, they a re fixed or nearly fixed in this population.