A PhD project at the Norwegian School of Veterinary Science has been studying the genetics behind mammary tumours in dogs. Breast cancer is the most common form of cancer in female dogs.
Kaja Sverdrup Borge’s PhD project has led to the identification of genetic changes associated with these types of tumour.
Borge studied known risk genes in dogs to learn more about the genes that predispose dogs to canine mammary tumours. These genes are already known to be linked to cancer in humans. Borge discovered that there was a large variation in these genes from breed to breed. Some of the variants proved to have a detrimental effect and could lead to a potential change in the risk of developing cancer.
Borge compared the incidence of these genes in different groups of English springer spaniels with and without mammary tumours. The genes were also studied in another group of dogs from breeds having either a high or low incidence of mammary tumours. The results of these analyses indicate that variants of the oestrogen receptor gene are associated with the risk of developing mammary tumours in dogs.
Borge examined canine mammary tumours in order to identify mutations which have arisen in tumours and may therefore be involved in the development of cancer. She focused on changes in the number of gene copies where there was either a decrease or increase in gene areas in the tumours.
She found a large number of mutations and the number of aberrations increased, the more malignant the tumours turned out to be. She detected major cancer genes known to occur in humans but also identified new areas. Borge also demonstrated that linking detailed histopathological parameters from mammary tumour diagnostics to genetic mutations could help to chart specific genes that lead to the growth of tumours and to more malignant types of cancer.
Increased knowledge about the genetic changes which cause cancer is essential for the prevention, diagnosis and treatment of the disease. Because of the similarities between carcinogenic gene mutations in both canine and human breast cancer, studying breast cancer in dogs also has benefits for the study of breast cancer in humans.