Feline Fibrosarcoma

Tuxedo cat
Tuxedo cat (healthy but may be suffering a mild form of Feline Hyperesthesia)- see below for rights

Feline Fibrosarcoma are highly malignant, highly aggressive, tumors. The word “sacrcoma” means cancer of the supportive or connective tissue. Just below the dermis of the skin is the epidermis. The epidermis is made up of connective tissue. See the drawing:

Skin Layers

Above: The layers of skin showing the epidermis, dermis and subcutis. See rights to publish this picture

Feline Fibrosarcoma occurs in the skin and is the sarcoma most commonly associated with vaccines. It is a vaccine associated sarcoma (VAS). VAS has resulted in new cat vaccine recommendations. The cancerous growth can be large when first noticed and also be infected and/or ulcerated. It may

It has been found that inflammation of the subcutis (see drawing above) precedes the cancer and inflammation occurs more often when the vaccine contains a substance called an adjuvant (a substance that catalyzes or modifies the action of the vaccine). A new rabies vaccine has been brougth out I understand as a result with less incidents of inflammation.

Feline Fibrosarcoma (not necessarily occuring as a result of a vaccination) can invade the bone and cause lameness by the destruction of the medulla and cortex. The medulla ossea is the bone marrow in the hollow part of the bone. The cortex is the outer shell of the bone.

The prognosis is described as “guarded to poor” (src: http://priory.com). In other words not too good. This source also says that the tumor free period after treatments which includes surgery to remove the tumor, chemotherapy and radiotherapy if appropriate and repeat surgery is no more that 5 months and surival for the cat no longer than 16 months.

The Wikipedia author says that the period before recurrence of the tumor after surgery depended on the extent of the surgery. The more extensive the greater the success in terms of time free of the tumor. For extensive surgery the time was an average of 325 days and for less extensive surgery it was 79 days. It would seem to be a trade off as extensive surgery could have deliterous consequences for the cat that outweigh the benefits. Either way the time free of the cancer after surgery seems short to me. This would beg the question, “Is it worth it?” I don’t have the answer, the veterinariain should.

A factor in deciding surgery will no doubt be whether the disease has spread (called metastasis). Apparently one in five or 20% of cats with Feline Fibrosarcoma suffer the consequences of the cancer speading usually to the lungs, and/or lymph nodes or skin.

A combination of surgery and intradermal LPSp (lipopolysaccharideand oral cyclophosphamide was referred to on this web page. Cyclophosphamide is a chemotherapy drug given to humans to combat cancer. It is not clear if this treatment (carried out some time ago I suspect) was adopted or had improved chances of success.

From Feline Fibrosarcoma to Cat Health Problems


  1. Wikipedia
  2. Veterinary Notes For Cat Owners by Dr Trevor Turner and Jean Turner VN
  3. www.medcyclopaedia.com (definition)
  4. http://priory.com/vet/feline.htm
  5. www.cancerbackup.org.uk


Photograph of layers of skin: this is published under a Wikipedia commons license and is in the public domain in the USA. If it is a problem to someone please tell me and I’ll deal with it promptly. Thanks.

Photo of Tuxedo cat – you are free to use this photo provided it is not hot linked (i.e. please down load and then upload to your server). Also I’d appreciate a link to this page.

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About Michael Broad

Michael is retired! He retired at age 57 and at Aug 2018 is approaching 70. He worked in many jobs. The last job he did was as a solicitor practicing general law. He loves animals and is passionate about animal welfare. He also loves photography and nature. He hates animal abuse. He has owned and managed this site since 2007. There are around 13k pages so please use the custom search facility!


Feline Fibrosarcoma — 8 Comments

  1. my cat had surgery in may 2012 for fibrosircoma. he’s losing a little hair now at the site of surgery. does this mean the cancer is coming back?

    • I’ll answer as best I can from two angles:

      • Cat Owner’s Home Veterinary Handbook at page 131 “Diseases with Hair Loss” makes no reference to fibrosarcoma causing hair loss.
      • If the hair had grown back in that area after the surgery but there is now a gradual hair loss in the same area, to me, on a common sense basis, it would indicate that some sort of damage has occurred to the cells in that layer of the skin (the dermis). This may be caused by cancer it seems to me.
    • I would have thought there might be some very localised hair loss where the cancer was removed. But I would also have thought that this would not be hair loss as such but a permanent lack of hair at the precise site of the operation. Perhaps there is some damage to the skin in the area caused by the operation that was unintended. This is a pure guess. Like I said if the hair grew back in the area and then failed to grow and was lost it would indicate a disease in that area.

  2. My kitty was diagnosed with fibrosarcoma in February 2012, although the surgery was done prior to the diagnosis for reasons of being proactive and the tumour being relatively small. When my kitty had the surgery done, the vet removed a larger area than needed. The tumour was the size of a nickel and the incision was 5-6 centimeters long. I’m going to assume that your vet removed your kitty’s eye as a proactive measure. The greater the surgical margin, meaning the more aggressive and drastic the intital surgery is, the better chance that it will not spread or return. This type of cancer is unfortunately aggresive, however, if you keep taking your kitty for checkups, then a return of cancer can be caught right away and removed again. All the best to you and your kitty! My thoughts are with you!

    • This is more of a question than reply. My cat has a lump on her back and vet is sending me to a surgeon and oncology clinic tomorrow. I have read a lot on fibrosarcoma tumors and wondered how your kitty was doing. I had to euthanize my baby girl in june (she was about 13), my baby boy last wednesday (approx 14) and now I get this new. I have spent a absolute fortune on vets, in home euthanasia and cremations. Will have tumor biopsied and will need to make decision on what to do. Seems like cases have had tumor reappear in few months even with chemo and radiation. Don’t want to go there and cant afford it. If u can help at all please email me please. Thank u, Renee

  3. few months ago my cat has been diagnose by tumour Fibrosarcoma in his lower eyelid,Recently on the 26th june 2012 he had an operation by remove his right eye.do you think the tumour is all gone and if not after how long it thr tunour comes back?

    • Hi Carmen. It seems that the tumor was large as your veterinarian removed the entire eye rather than part of the eyelid. That might indicate that there is a greater chance that the cancer may have spread. If caught early the prognosis is better.

      However, I am unable to answer your question. I would have thought that your vet couldn’t answer it with certainty.

      I am afraid you will have to watch your cat and wait or ask your vet some more questions!

      Thanks for visiting and asking. And good luck to you both.

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