Wednesday, July 3, 2013

Three things I learned: lymphoma in cats

Lil' Puss Fawcett, who passed away due to complications of suspected lymphoma. As you can see, life was pretty awesome for Lil.


The Animal Referral Hospital recently hosted an educational information at the Homebush hospital. One of the speakers, oncologist Sandra Nguyen, talked about lymphoma, a malignant transformation of B or T lymphocytes. There are other round cell tumours in companion animals (mast cell tumours, transmissible venereal tumours, histiocytic tumours etc) but in cats lymphoma is the most common. I have a personal vendetta against this affliction as it claimed my gorgeous cat Lil two years ago.

Sandra N is a former classmate of mine and it was great to see her command the floor while everyone took copious notes. I learned a lot, notably that

  • Cats that are FeLV positive are 60 times more likely to develop lymphoma than FeLV negative cats; and cats with both FeLV and FIV are 80 times more likely to develop lymphoma.
  • The talk helped clarify some salient points regarding treatment and prognosis of high and low grade lymphoma. High grade lymphoma is more readily diagnosed via fine needle aspirate and cytology (biopsies are usually required to differential low grade lymphoma from IBD); only 50 per cent of cats with high grade lymphoma respond to treatment with a median survival of 6 months while 98 per cent of cats with low grade lymphoma respond, with a median survival of 704 days. Response to treatment is the most reliable prognostic indicator, but cats with low grade lymphoma may take 2-3 months to show a robust clinical response. In cats, there is no real difference in the prognosis between B and T cell lymphomas. (BTW treatment for low grade lymphoma is often oral medication - people get frightened off by the word "chemotherapy" but are surprised to hear that it can be extremely straightforward and administered at home).
  • Unlike people, who experience a higher rate of side effects associated with chemotherapy, around 30 per cent of cats develop side effects to chemotherapy, only 5% require hospitalisation and death due to chemotherapy complications is likely less than 1%. Cats are less likely to develop sepsis with a low while cell count than dogs.

When detected early, many lymphomas can be treated and managed quite well with excellent quality of life for cats. Of course cancer can be an absolutely unforgiving disease that wins despite our best efforts, but in many cases there is potential to give an affected cat extended quality of life.

5 comments:

  1. Thanks for the very interesting and informitive post.

    Reading it made me think on the ethical issue of treating a loved pet with (still) highly toxic chemotherapeutic meds for only a limited survival benefit of a median 6 months.

    I can relate your heartache of losing a pet to cancer, as I lost my Lovely German Shephard to Breast Ca. She did undergo a radical mastectomy but I am not sure if I would've considered treatment with a chemotherapeutic agent.

    Whether its ethical to consider chemotherapy for what seems like limited life prolongation with potential risk of side-effects.
    30% Still sound like a big number, one in three,in other words. And, whether its a pratice to discontinue the treatment if the pet develops side-effects?

    Would love to hear your opinion on this.

    Thanks, Rene.

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  2. Thanks for the comment Rene. I am so sorry to hear about the loss of your dog. It hurts when they are taken so early, and sometimes even more so when you've tried treatment and it doesn't necessarily yield the outcome you so hoped for.

    Treating cancer with chemotherapy is such an emotional issue, esp as most of us also have experience of seeing a person having chemotherapy (I read a fantastic book by Jo Hilder, "A Beginner's guide to things NOT to say to someone who has cancer"...which suggests that the incidence of cancer in people is almost one in two) and it can be very traumatic. People often say "I would never put an animal through that". But its not that simple.

    The big issue is consent. Human patients in general can give consent (of course, neonates, toddlers, older people or others whose faculties might be compromised cannot). So we tend to blast them with curative doses of radiation or chemo which are more likely to cause side effects. The deal goes something like this: this will likely make you quite sick however it will increase your chances of an improved length or quality of life by X per cent. You can't make a deal like that with an animal, so much treatment for cancer is "palliative". Doesn't mean it isn't worthwhile. I've seen plenty of animals do brilliantly on chemotherapy with minimal side effects (eg occasional nausea which we can manage, occasional diarrhoea). Others do get more severe side effects, eg haemorrhage, infection.

    Whether chemotherapy is ethical depends on a) the patient (a feral cat is not going to appreciate multiple vet visits and the stress may be more than the cat can take); b) the cancer (what is the likelihood of restoration of quality of life or cure); c) what is the likely prognosis in THIS patient (ie are there multiple conditions? how old is the patient) and d) what is the chemotherapy?

    Some people are shocked that chemotherapy may just involve a daily tablet or medication.

    Yes, treatment may be discontinued in some cases, but in other cases side effects can be managed (eg anti-nausea medication). The most common cancer treatment I perform is surgery - removing a tumour, where it is well circumscribed and has not spread, is often curative.

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  3. Every treatment for any disease has a potential side effect; whether you are treating cancer or not.

    In my experience, most of my patients that have side effects experience them for a short period, and it is usually mild.

    In the case where a side effect is impacting quality of life, we certainly dose reduce, or stop therapy. Swapping to a different drug is also a consideration.
    Sandra N

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  4. Thanks for your detailed reply, Dr Anne.
    Rene

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  5. Great post Anne (and Sandra N!) thanks for that. I feel like I learned a couple of things just from the post.

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