My Cat Has Cancer: Staging and Grading the Tumors

My Cat Has Cancer: Staging and Grading the Tumors

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Dr. Phil Zeltzman is a traveling, board-certified surgeon in Allentown, PA. His website is He is the co-author of “Walk a Hound, Lose a Pound” (

AJ Debiasse, a veterinary technician in Stroudsburg, PA, contributed to this article.

Few things are as devastating as learning that your beloved cat has cancer. Yet, despite the emotional rollercoaster, you must be strong and make the best possible decisions for your beloved pet. Two of the most important concepts you need to understand when discussing cancer with your family veterinarian, a surgeon or an oncologist (a cancer specialist) are "grading" and "staging" of the cancer.

Staging a tumor
Staging is a way to find out, with as little doubt as possible, if a tumor has spread anywhere in the body. Staging is determined by your family veterinarian, a surgeon or an oncologist; it’s based on several factors:

  • From experience, veterinarians know that some tumors are more likely to spread than others. Benign tumors don’t spread. Some cancerous tumors rarely spread (e.g., fibrosarcoma). Other cancers spread quickly (e.g., bone cancer).
  • Chest X-rays are an easy way to evaluate spreading to the lungs. A fancier test, that can show much smaller masses, is a cat scan of the chest.
  • Sometimes, tumors in the belly (e.g., hemangiosarcoma in the spleen) tend to spread to the liver, so an ultrasound is often recommended to “explore” the entire area.
  • Some tumors (e.g., oral cancer) first spread to a nearby lymph node, which can be suspected (but never proven) by doing a thorough physical exam on your cat.
  • Other tumors (e.g., malignant melanoma) most often spread to the lungs, which act as a filter for tiny cancer cells.

Grading a tumor
The grade describes how aggressive a tumor is, including how likely it is to spread. Grading is judged by a pathologist, after analyzing a tumor sample under the microscope. There are different systems to grade a tumor. Simply said, there are three basic grades:

  • Grade 1 describes a mass that is cancerous but usually localized, and not very likely to be metastatic or metastasize (i.e., spread to other organs).
  • Grade 2 is a tumor that is more aggressive; it may or may not spread.
  • Grade 3 is the most aggressive type with a high likelihood of spreading.

Other tumors are graded differently:

  • “Well Differentiated” are better
  • “Moderately Differentiated” or “Poorly Differentiated” are worse

Others are called:

  • Low grade
  • Medium grade
  • High grade.

Your veterinarian will explain based on your cat’s situation.

Practically, the most effective way to grade a tumor is to take a biopsy, or even remove it all, and send it out for analysis under the microscope. A biopsy is very different from a needle sample of a tumor (fine-needle aspirate), where cells are drawn out with a needle and placed on a slide to be examined under a microscope. This test can be helpful but does not provide a grade for the tumor. We need a larger sample of the mass to achieve that.

Grading and staging tumors are inter-related
Interestingly, there is a relationship between the grade and the stage of a tumor. For example, a grade 1 tumor is the least likely to spread to other organs, with a better survival rate. On the opposite end, a grade 3 tumor has a high risk of spreading, and therefore the outcome will logically be worse.

Treating your cat based on grading and staging
When making a decision on how to treat your cat, it is very important to understand what grade and stage we are dealing with, because the treatment for each type is different. This information may also give you an idea of the likelihood that the cancer returning. The good news is that through the years, veterinarians have made impressive cancer treatment advancements that can be customized to your cat’s specific cancer type. The treatment may include surgery, chemotherapy, radiation therapy and nutritional changes.

It is important to understand that cancer doesn’t always follow the rules. This information is a general guide. Unfortunately, staging and grading don’t always give you a guarantee of what the future may hold. It’s also extremely important to avoid procrastination and to treat in a timely fashion regardless of the findings. The sooner cancer is diagnosed, and the sooner it is treated, the more options veterinarians have, and the more successful we will be.

  • How do we determine if my cat’s mass is cancer or not?
  • What is the stage of this mass?
  • What is the grade of this mass?

If you have any questions or concerns, you should always visit or call your veterinarian -- they are your best resource to ensure the health and well-being of your pets.

Cancer in Cats: Types, Symptoms, Prevention, and Treatment

WebMD veterinary expert answers commonly asked questions about cancer in cats.

Although cancer isn’t as common in cats as it is in dogs, it still affects a number of our feline friends. And because cats have a tendency to mask illnesses, it can be harder to detect. This often leads to later diagnoses and more difficult and costly treatments. So we talked to Dave Ruslander, a veterinary oncologist and past president of the Veterinary Cancer Society, about feline cancers and the latest treatments for cats diagnosed with the disease.

Q: How common is cancer in cats? What are some of the more common cancers found in cats?

A: Cancer in cats is less common than cancer in dogs. It’s probably half the rate that we see in dogs. But when we see cancer in cats, it tends to be a more aggressive form.

One of the most common cancers we see in cats is lymphoma, which is associated with the feline leukemia virus (FeLV). Even though there’s a vaccine for feline leukemia now, we still see a number of cats that have been exposed to it, and exposure greatly increases a cat’s chance of developing feline lymphoma.

We also see oral squamous carcinoma, similar to what people get. We see a tumor called fibrosarcoma, or soft tissue sarcoma, which is a tumor developing in muscle or in the connective tissue of the body. That’s the one associated with injections and vaccinations, which some people call injection-site sarcoma.

We see other kinds of tumors as well, but they are much less common -- lung tumors, brain tumors, nasal tumors, liver tumors. We don’t see as many mammary tumors these days because so many people have their cats spayed now. So all of those are just a smattering here and there.

Q: What are some of the symptoms of feline cancers?

A: Cats are tricky because they hide disease well. Externally we can see lumps and bumps. Vomiting and diarrhea are common signs of gastrointestinal lymphoma. Difficulty in breathing can be a sign, because some cancers can cause fluid in the lungs.


Sometimes it’s just a refusal to eat and weight loss, a rough coat, or just generally what we call a failure to thrive. It’s always best, if your cat is acting ill or lethargic for any period of time, to take it to your veterinarian to be checked out.

Q: Is it difficult to diagnose the type of cancer a cat has contracted?

A: With a biopsy the pathologist can usually tell us the type of cancer. But sometimes it’s not so clear. And sometimes people are reluctant to go forward without a firm prognosis. Often we can’t go forward until we know what the actual subtype is. It can take some special testing or some special stains for us to delineate the type of cancer, and sometimes people just aren’t willing to do that.

Q: What’s causing the high cancer rates in our cats?

A: We really don’t know what causes most cancers. There are a few, like the feline leukemia virus, which is the big player in cancer etiology in cats. But I don’t know that we have the answer for what causes most cancers in cats.

We do know people are keeping cats longer. Cats are living longer, so of course we see more cancer in cats just because we see more cats. But even in older cats, cancer is more sporadic than it is in dogs.

Q: Can household chemicals or other common items, like bug sprays, cause cancer in cats because they walk through the residues and then lick their feet?

A: There may be environmental causes. There have been some studies looking at secondhand smoke. There have been issues of cats grooming themselves developing oral cancers. But they really don’t know if it’s because they’re taking some toxins from the environment into their body that way or not. There are still a lot of questions about environmental issues.

Q: Are some cat breeds more prone to cancers than others?

A: No, we don’t really recognize breeds of cats being at increased risk of cancers like in dogs. However, white varieties of certain cat breeds are more prone to squamous cell carcinoma, usually on their ears and face.)


Q: If my cat has cancer, does that mean they are going to die?

A: No, but many of the cancers we see in cats are more aggressive than those we see in dogs. So early detection and treatment are very important.

Q: What are the treatments for cats with cancer?

A: We have surgery, which is the most common treatment for any kind of lump or bump that needs to be removed. Chemotherapy is used most commonly in the management of lymphomas. But it’s also used when we have aggressive tumors that have spread to lymph nodes or other organs.

We use radiation therapy in situations where we can’t remove the tumors, for example brain tumors and nasal tumors.

Q: Are we seeing advancements in the treatment of feline cancers?

A: Yes, but because historically people tended to do less for cats than they did for dogs, the advancements have been slower. But we’ve had advancements with radiation therapy, new and novel chemotherapy approaches, and new surgical approaches as well.

But we haven’t seen as many drug advances for cats as we’ve seen for dogs. A lot more of the research dollars go to dog cancers than go to cat cancers.

Q: How much does it cost to treat a cat with cancer?

A: Probably $500 to $1,000 to do the initial diagnostic testing. Then it costs anywhere from $800 to $2,000 for surgical approaches. Chemotherapy is $2,000 to $3,000, and then radiation can be $5,000 or $6,000. (Note: These are costs for treatment at a specialist. Prices at a general veterinary practice may be much less. Costs may also vary a lot depending on where you live.)

Q: If treated, what’s the cure rate for cats with cancer?

A: That’s hard to say because there are so many different types of cancers and so many variables. But I would say overall the survival rate for cats, if we’re including every type of malignancy, is probably less than 50%. But it all depends on the tumor type, when it is found, and how it is treated.


I would recommend, whenever an animal is diagnosed with cancer, that the owner consult with a veterinary oncologist. Things are changing so fast, not just in terms of treatments but also clinical trials or novel treatments, that there may be treatments available that most veterinarians aren’t aware of. You may think there’s nothing that can be done, but things are changing all the time.

Q: What can I do to prevent my cat from getting cancer?

A: Spaying your cat will drastically reduce their chance of getting mammary cancer. Preventing the development of feline leukemia, either through vaccinations or making sure when you get a cat that the cat hasn’t been exposed to feline leukemia, will decrease the likelihood of developing lymphoma.

But it’s so hard to say how to prevent something when you don’t know what causes it most of the time. So early evaluation and detection is probably the better approach in terms of improving outcome.

My Cat Has Cancer: Staging and Grading the Tumors - pets

Lymphosarcoma is a tumor caused by a cancerous proliferation of lymphocytes or, cells that normally function in the immune system. This is a very common tumor in cats and can present in a variety of ways. At one time, feline leukemia virus (FeLV) was a leading cause of LSA in cats and typically young cats were infected. Now that the incidence of FeLV has decreased cats still develop LSA but it is generally older cats and different forms. The Feline aids virus (FIV) has also been shown to increase the risk of a cat developing LSA six times over a non-infected cat. Any breed of cat can develop LSA. The cause of the disease unrelated to FeLV or FIV is unknown although environmental smoke exposure has been found to increase a cat’s risk of LSA, and a possible link to long standing inflammatory disease has long been theorized.

What you might see/ Clinical presentation

Cats with LSA present with a variety of signs because lymphocytes can be found in nearly every organ in the body. Also, cats seem to have more forms of LSA in atypical locations or not in normal lymphoid tissues, as compared to other species. Most species including man present with large lymph nodes, but this is a rare form of LSA in cats. Young cats typically present for masses in the chest cavity and owners notice signs of difficulties breathing or vomiting of food. Older cats develop the tumor in their intestines quite commonly and owners may notice signs such as weight loss, diarrhea or vomiting. They also can however develop LSA in areas as diverse as the nasal passages, kidneys, spinal cord, liver, eyes, or a single lymph node, and the signs seen will be more specific for the organ affected. Because cats present with such a variety of organs affected there is no valid staging system for feline LSA and a cat diagnosed with the disease will more likely be staged by the organ affected (eg. gastrointestinal LSA, mediastinal LSA etc.)

Biological behavior of LSA

Even though many cats present with only a single site of involvement, LSA is viewed as a systemic disease. Lymphocytes in their normal functioning capacity travel throughout the body and as a cancer the disease is also moving though not in a classical sense "metastasizing". Even if a tumor diagnosed as LSA has been surgically removed the disease is not gone.

Clinical staging (determination of the extent of the tumor)

Because of the organs that LSA commonly involves, staging a cat with a LSA can involve aspiration of one or more lymph nodes or masses, thoracic radiographs abdominal radiographs or ultrasound (to look for big nodes in the abdomen and to look at the liver and spleen), or bone marrow examination. Obtaining blood for a complete blood count and biochemical profile, FeLV, FIV, and a urinalysis is always advised as these can help assess overall health and provide information that potentially influences treatment recommendations. Sometimes, special stains to determine if the LSA is of B-cell or T-cell origin (B-cells and T-cells are specific types of lymphocytes) are recommended because of prognostic significance, although treatment recommendations may be the same for either type. Staging the disease can be critical in choosing treatment protocols.

Treatment options

Chemotherapy should always be considered a critical part of the treatment for LSA. The best responses in terms of length of tumor control and survival are generally seen with protocols that entail administration of more than one chemotherapy drug, although there are approaches that involve administration of a single drug. Chemotherapy drugs commonly used include: doxorubicin, vincristine, cyclophosphamide, prednisone, and L-Aspariginase, but many others are also used. Some protocols are very aggressive and relatively short (six month total) and others are less aggressive but extend for one to two years. The decision of which protocol is to be used does depend on the results of the tumor biopsy (not all LSA is the same) and the staging results. Thankfully, the chemotherapy generally act quickly so that even cats with sever signs can have relief fairly soon after starting therapy (sometimes as quickly as 24 hours). Surgery is sometimes recommended as a part of the treatment but this is usually either to reach a diagnosis or to remove a potentially life threatening problem (for example intestinal rupture due to a tumor mass). Surgery is never curative and should always be followed by chemotherapy to best extend the cat’s life. Radiation can also play a role in the treatment of very localized LSA. The primary site most benefiting from radiation therapy is nasal LSA.


Cats with LSA have unpredictable responses and survivals. Depending on the site of the tumor, mean survivals with chemotherapy range from 6-9 months. The problem is that this is only an average and most cats tend to do either much worse or much better. Young cats, FeLV negative, with mediastinal LSA are quite regularly cured with chemotherapy cats with LSA in their central nervous system typically have a bad prognosis, but most other forms of LSA in cats have unpredictable outcomes. Generally it is best to at least try a chemotherapy protocol because it may be the only way to see how an individual cat will do. Cats often do not enjoy receiving chemotherapy, but veterinary oncologist try hard to make the regime tolerable for each feline patient even if it means modifications in a protocol.

Future treatment options

New protocols are tried in feline lymphoma but results have been similar with each drug regime investigated. Most likely our survivals will always be similar until we either accept greater toxicity (meaning most cats will be very sick from the treatment and some may even die), or a completely novel treatment is invented. Using half or whole body radiation therapy may prove helpful. The development an antibody specific for cat lymphoma, which could recognize all cat lymphomas and yet no normal lymphocytes, and be attached to a toxin or other cell killing mechanism, is a far off dream.

Key points

LSA is one of the most chemotherapy-responsive tumors seen in veterinary medicine and cats can tolerate chemotherapy relatively well, or protocols can be modified so that an individual cat can maintain a good quality of life while on chemotherapy. Unfortunately we have few strong predictors of which cats will have good responses to chemotherapy and long survivals, and survival is therefore difficult to estimate at the outset. Often the only way to know how a cat will respond to treatment, is to start treatment.

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Other Symptoms of Cat Cancer

  • Foul odor - healthy cats don’t smell.
  • Persistent sores - sores that don’t heal, need to be looked at by a professional.
  • Difficulty with bathroom chores
  • Loss of appetite
  • Unexplained bleeding
  • Lethargy

You may read this list of symptoms and they think they’re the same for many health concerns and you’re right. They are. External symptoms of cat cancer can be subtle. Your best course of action for prevention is a healthy lifestyle and regular check ups for your cat. We recommend twice a year wellness visits for cats 8 and older.

You can find out more about cat cancer here and you can book an appointment here.

Palliative care is very important as it often helps prolong a cat's quality of life. Treating the symptoms as they arise, such as weight loss, lack of condition, lack of appetite and pain, can greatly extend your kitty's quality of life. Cancer often robs muscle mass from animals due to malnutrition, and many cats are unwilling to eat when they do not feel well. Your veterinarian can prescribe a diet that's palatable to your cat or provide medications to increase the cat's appetite.

Pain management is important for your cat's quality of life during end-stage lymphoma. Your veterinarian or veterinary oncologist may prescribe pain medications for your cat. In some instances, prednisone and palliative radiation may help mitigate pain.

Watch the video: Cat Mammary Tumors: Signs, Symptoms, and Treatments: Vlog 92


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