Chemotherapy is commonly injected into tumours directly. The benefit is no risk of sickness-type side effects and a greatly increased dose (more effective) to the tumour. The down side is the drug only penetrates a few millimetres from wherever its placed and that large masses have very high pressure inside them which often limits drug absorption. In my practice it is most often used for 'mopping up' surgery sites when there is microscopic cancer remaining, but more aggressive surgery is not desirable or possible. Usually I combine it with electroporation, which is placing an electric current (safely) through the tumour which makes the cancer cells absorb the drug better. The total process is called electrochemotherapy. In some cases this is a single treatment, in others it is repeated up to 4 times at 1 to 2 week intervals. The tumours that have the most evidence base for this approach are soft tissue sarcomas (e.g. fibrosarcoma), mast cell tumours, squamous cell carcinomas and oral melanomas.
_________________ _______________ Dr Ken Wyatt BSc BVMS FANZCVS Specialist Veterinary Oncologist Perth Veterinary Oncology
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