Anaplastic carcoma

Question
Our vet removed a large lump from our 6.5yr old spayed male rabbit, Pongo 2 days ago, and yesterday advised pathology showed the lump was an anaplastic sarcoma.

There was only a 1mm margin around the tumour, and ideally he would go back in and removed surrounding muscle etc from the site.

However Pongo took 3 times as long to recover from being anaesthetised, which made the vet feel it is too big a risk to put him under again at his age.

Everything I've read suggests this type of sarcoma is aggressive, and there's little doubt its filaments were left behind with just a 1mm margin.  

Pongo is in fine and bright health otherwise, has recovered from his surgery (with the wound healing nicely already), but I want to know if at his age, whether radiation treatment might just diminish his currently high quality of life with a bad result anyway?

Answer
Dear Helen,

Radiation has its own risks, so you might want to discuss this with your veterinarian.  You don't say where the lump was, but if it's on a limb and continues to grow back, then amputation could be something to consider, rather than constant surgeries.  At 6.5 years, he's not really old.  While no surgery is 100% risk free, if he's in generally good health as determined by your vet (bloodwork, etc.), then it would be better to try this than to give up.

Sarcomas like this are often only locally invasive, not metastatic.  So if you can remove a large area where the tumor is, then the problem may be permanently solved.

Discuss radiation with your vet to see if this would do more harm than good. Some people have reported good success, but it depends on the type of cancer and its location.  Radiation is ionizing, and as such is a carcinogen itself.  So long-term effects could show up just due to the radiation, though again--it's better than dying in the short term from an aggressive tumor.

I hope this helps.

Dana