Distribution of nuclear DNA-content in canine mammary tumours

It is well established that nuclear DNA-content contributes valuable information concerning tumour behaviour in a vast number of human neoplasms (compare Auer and Zetterberg, 1984 and Zetterberg and Auer 1984 for review). The authors have attempted for the first time to apply this concept to clinical veterinary medicine and in the present investigation 17 dogs with mammary tumour were studied retrospectively. Microspectro-photometric DNA-measurements were performed and correlated to the clinical course defined as distant recurrence free interval. The results suggest that a relationship exists between nuclear DNA-content of the breast cancer cells and prognosis. Tumours exhibiting DNA-values within the limits of normal tissue correlate with a favourable prognosis in the sense that all dogs with diploid tumour cell DNA-content under study had survived for more than one year without recurrence of the tumour. In contrast 50 per cent of the tumours with increased and scattered DNA-values developed metastasis within one year whereas the other 50 per cent were disease free after this period. It is therefore proposed that cytophotometric analysis of DNA may be used in the assessment of prognosis in dogs with malignant breast tumours.