What is cancer?

Cancer isn’t a single disease, it is a whole complex of diseases typified by uncontrolled proliferation of abnormal cells.  All cancer is genetic in that it requires one or more genetic mutations to initiate the disease process, but it isn’t necessarily inherited.  Environmental factors that damage DNA can cause carcinogenic mutations and chromosomal abnormalities.  In older individuals there has been more opportunity for these changes to occur so the old are more likely to develop cancer than the young.

 Is cancer genetic?

Yes, in that something has altered the DNA, but this unlikely to happen with the germ-line (reproductive) cells so is limited to the individual.  However, there are some cancers that clearly follow family lines.  In humans certain gene forms are known to be associated with certain cancers.  In purebred dogs cancer is more prevalent in some breeds than others and clearly can follow family lines though we don’t know which genes are involved.

If any single cancer occurs in multiple members of the same family, especially if those dogs lived in different environments (i.e. different owners and placaes) one should be suspicious that some sort of genetic predisposition is at play.  We have known since the mid-2000s that we have two inherited cancers in Aussies:  Hemangiosarcoma and lymphoma, both of which have been increasing in frequency. (See ASHGI’s 2017 longevity survey.)

Are all tumors cancerous?

No.  Some tumors are benign.  Two examples are lypoma, fatty tumors found under the skin and usually in older dogs, and meningioma, a genign tumor of the brain.  However, a benign tumor can be a health issue depending on what it is, whether it is enlarging, and where it is located.

Are there any environmental factors connected to cancer in Aussies?

The 2007 ASHGI cancer survey found no significant relationships found between environmental factors and cancer, though there was a slight correlation between urban and rural spraying programs and lymphoma.  Research on that cancer in humans has indicated that there may be a similar connection but at this point there is no conclusive evidence for dogs.

Is cancer autoimmune disease?

No.  The immune system is important in the body’s defense against cancer and failures of the immune system can contribute to cancer but it is not autoimmune.  Autoimmune diseases are those in which the immune system attacks its own body.  They do not cause the abnormal cell proliferation typical of cancer.