Cancer has been defined many ways, usually by medical scientists. Cancer is defined by its ability to grow despite biological safety measures which should prevent it, such as anti-growth signals and pre-programmed cell suicide strategies. This scientific definition is important to medical scientists who use this knowledge to better understand and treat cancer. It is also important however, to state that cancer is defined in other ways. For those who have experienced it in some way, it may be defined by a memory of a loved family member or pet. For others, cancer is associated with stigma based on assumptions that treatment causes significant suffering. It is important to all of us who are prepared to discuss cancer that we are aware of the possible ‘meanings’ of cancer to other individuals.
How Often Does it Happen?
Often. Data have shown that the incidence of cancer in dogs is similar to the incidence of cancer in humans. Dogs have known risk factors, just like humans do, though dogs do not smoke tobacco or drink alcohol. Some breeds are known to have particular risk factors. In Newfoundlands, osteosarcoma, or bone cancer, has been reported to be the most common cancer seen. It is important to state that the frequency of osteosarcoma in Newfoundlands does seem to be less than other predisposed breeds.
How Do I Recognise it?
Cancer is a term that describes a vast number of different diseases. The single thing they all have in common is that the cancer cells grow despite the fact that they are not supposed to. Therefore cancer can present in a patient in an infinite number of ways. Some healthcare resources describe ‘cardinal signs of cancer’. These are helpful up to a point but they are by no means proof of the presence of cancer. The identification of one or more of these signs should prompt an owner to seek veterinary attention. I prefer to separate my list of these signs into ‘focal’ or anatomically isolated signs, and ‘systemic’ or anatomically generalised signs.
Focal signs include:
Skin lump or swelling under skin
Treatment resistant lameness
Systemic signs include:
Once again, presence of one or more of these signs is NOT tantamount to a diagnosis of cancer. Further investigation must follow or there is a danger of assuming a worse diagnosis than is really the case.
What to Do?
If you suspect or are worried about cancer, seek a veterinary appointment. Following this you will be advised to either monitor the lesion or sign, to consent to a biopsy or to allow further testing such as x-rays or blood tests. As a general principle, there are very few situations in which a simple ‘fine needle aspirate biopsy’ or ‘FNA’ is not the diagnostic test of choice. There are far too many instances when patients are subjected to removal of a lump before its identity is known. Similarly, there are too many instances when patients’ lumps are simply monitored to see if they grow, only for the opportunity to cure them to be lost. Fine needle aspirate biopsy is a minimally invasive test that can be performed conscious in most cases in most anatomic sites. It is always better to know the nature of a problem before defining a treatment plan though it is accepted that this is not possible in all cases.
If a diagnosis of cancer is made and the practitioner in question is not familiar with the range of treatment options available and the potential risks and benefits associated with those options, they can contact a veterinary oncologist to discuss the case. Most veterinary oncologists in the UK freely offer advice to veterinary colleagues to help in the management of their cases.
Gerry Polton is the Consultant Veterinary Oncologist at North Downs Specialist Referrals, the multidisciplinary specialist veterinary hospital in Surrey. Gerry is experienced in all aspects of cancer care and has specialised in veterinary cancer since 2002. He regularly lectures both nationally and internationally on all aspects of veterinary cancer. He has particular interests in lymphoma, leukaemia, mast cell tumours, tumours of the anal sac, novel therapies and cancer prognostics.
Gerry Polton MA VetMB MSc(Clin Onc) MRCVSNDSR
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