Search for a Genetic Link for Mammary Cancer in a Beagle Colony

Background: A possible genetic link for malignant mammary tumor (MMT) was investigated. Materials and Methods: Records of an internally-irradiated beagle colony followed from the early 1950's until about 1995 were searched and analyzed by standard statistical procedures. Results: Only a single ancestor yielded a “p” value (Fisher's Exact Test) for an overrepresentation among descendants with MMT at >0.025 (one-sided test), and the number of comparisons for the 169 ancestors where the relative fraction of animals with MMT was greater than that for non MMT dogs (61) suggests that this could have occurred by chance alone. Results of other statistical tests were not remarkable. Conclusion: No genetic link for MMT in this colony could be established with the available data. These findings may or may not be relevant to humans.