From episode 156 on the Surgery Feed. With Dr. Brendan Janssens.
“The 2 cm rule is completely irrelevant, and that has been shown in a couple of veterinary papers where the surgical dose was not predictive of outcome. You can take 5 cm around a tumour and be marginal, and take the risk of having an incomplete excision - so the 5 centimetres is irrelevant. What matters is: “Did you get a margin?”
Usually, I like to share things in this newsletter that clarify. This post isn’t one of those! Surgical oncologist Dr. Brendan Janssens questioned everything I thought I knew in our episode on surgical margins for superficial tumours, but I reckon every now and again it’s good to question our dogma. Did you know:
A study looking at soft tissue sarcomas in dogs showed that:
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For a low-grade tumour with a marginal resection (i.e. complete resection with no tumour cells at the cut edge) the chances of local recurrence is just 10%. In other words, you have a 90% chance of curing a dog with a very narrow resection.
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For grade 2 the chances of recurrence was 20 - 30%.
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For grade 3 it’s 75%. (Note, there were only 4 dogs in this group, so numbers may not be accurate.) The consensus is that if you have narrow margins for a high-grade tumour then that dog needs more treatment locally. The debate is still open regarding systemic treatment.
So where does that leave us practically? Back to Dr Brendan:
“I would probably still take the two centimetres if I could, but if I could only take a centimetre, I still think there's a high chance of getting complete excision. I wouldn't say to an owner: 'I can't get two centimetres, therefore your dog has incurable disease.’”
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