Cancer
A cancer diagnosis is one of the hardest things a cat owner can face. It's natural to feel frightened and overwhelmed — and equally natural to have a hundred questions all at once. The most important thing to know from the outset is that cancer in cats is not automatically a death sentence. Many cancers are treatable, some are curable, and even where a cure isn't possible, a great deal can be done to give your cat a good quality of life for as long as possible. This page is here to help you understand what cancer is, how it shows up in cats, and what your options might look like.
What Is Cancer?
Cancer occurs when cells in the body begin to grow and divide abnormally and uncontrollably. These abnormal cells can form tumours — masses of tissue that don't belong — and in malignant cancers, they can invade surrounding tissue or spread to other parts of the body through the bloodstream or lymphatic system.
Not all tumours are cancerous. Benign tumours stay in one place, don't spread, and are often manageable or removable. Malignant tumours are the ones that cause the most serious problems — they disrupt normal organ function, spread to new sites, and if left untreated, can be fatal.
Cancer can affect any organ or tissue in the body, which is why symptoms can be so varied and sometimes easy to mistake for other conditions. It becomes more common as cats age, though it can affect cats of any age.
The Most Common Cancers in Cats
Lymphoma is the most frequently diagnosed cancer in cats. It affects the lymphatic system — a network of tissues and organs that run throughout the body — and can occur almost anywhere, most often in the gastrointestinal tract, chest, or nasal cavity. Because lymphocytes circulate throughout the body, lymphoma can present in many different ways depending on where it develops. It is the most studied and best-understood feline cancer, and there are well-established treatment options available.
Mammary (breast) cancer is the third most common cancer in cats and is significantly more likely to be malignant in cats than in dogs — around 85% of mammary tumours in cats are cancerous. Unspayed females are at significantly higher risk, and spaying before the first season dramatically reduces the likelihood of mammary cancer developing. Any lump along the mammary glands — which run in two rows along the underside of the abdomen — should be checked promptly.
Squamous cell carcinoma (SCC) is a skin cancer most commonly seen in white cats, or cats with pale or thin fur on their ears, nose, and eyelids. It's caused by UV damage and often starts as a crusty, reddened area that doesn't heal, progressing to an open sore. Keeping sun-vulnerable cats indoors during peak sun hours and applying pet-safe sun protection to exposed areas can reduce the risk.
Mast cell tumours can appear on the skin or within internal organs. They're unpredictable in behaviour — some grow slowly and respond well to surgery; others are more aggressive. Any new skin lump should be assessed promptly rather than watched and waited on.
Signs That Might Indicate Cancer
Because cancer can affect so many different parts of the body, symptoms vary widely — and many overlap with other conditions. This is not a checklist to diagnose cancer at home, but signs worth discussing with your vet include:
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Unexplained weight loss, even if appetite seems normal
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A lump or swelling anywhere on the body — whether it appears suddenly or grows gradually
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A sore or wound that won't heal
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Changes in appetite — eating less, eating more slowly, or losing interest in food
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Persistent vomiting or diarrhoea
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Difficulty eating, swallowing, or breathing
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Lethargy or a noticeable reduction in activity
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Bleeding from any part of the body
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A swollen or distended abdomen
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Persistent bad breath — particularly if it worsens suddenly
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Changes in litter box habits
Many of these are symptoms of other, very treatable conditions — which is another reason why getting your cat checked promptly matters. Don't assume the worst, but don't delay either.
Treatment Options
There is no single approach to treating cancer in cats — the right plan depends entirely on the type of cancer, how advanced it is, your cat's age and overall health, and what matters most to you and your family. Your vet, and in many cases a veterinary oncologist, will talk you through the options that apply to your cat's specific situation.
The main treatment approaches are:
Surgery is often the first-line treatment for solid tumours and aims to remove the cancer completely. For some cancers, surgery alone is curative — particularly when a tumour is caught early, is well-defined, and can be removed with clear margins.
Chemotherapy in cats works rather differently from chemotherapy in humans. Doses used in veterinary medicine are generally lower and side effects are much milder — most cats tolerate chemotherapy well and continue to live normally during treatment. Chemotherapy is most commonly used for lymphoma and is typically aimed at achieving remission rather than a cure.
Radiation therapy targets localised cancers with high-energy beams and is often used alongside surgery to reduce the risk of recurrence, or for tumours in areas where surgery is difficult.
Palliative care focuses on comfort and quality of life rather than treating the cancer directly. For cats where curative treatment isn't possible or isn't the right choice for the family, palliative care — including pain management, steroids, appetite support, and close monitoring — can allow a cat to live well for weeks or months, on their own terms.
There is no right or wrong answer. A decision to pursue aggressive treatment and a decision to pursue palliative care can both be the right choice, depending on your cat's individual situation and what matters most to your family.
Living with a Cat with Cancer
A cancer diagnosis changes things — but it doesn't necessarily mean your cat's remaining time has to be defined by illness. Many cats with cancer, particularly those on treatment or with slow-growing disease, continue to eat well, enjoy their routines, and have genuinely good days.
Keeping a close eye on your cat's quality of life is the most important thing you can do. Good quality of life means eating reasonably well, showing interest in their surroundings, having moments of comfort and contentment, and not being in unmanaged pain. Your vet can help you assess this — and there are quality of life tools available online that can help you track how your cat is doing over time.
When quality of life begins to deteriorate despite treatment, the most loving thing you can do is to have an honest conversation with your vet about end-of-life care and euthanasia. Making that decision before a cat is in severe distress — rather than waiting too long — is one of the greatest acts of kindness an owner can give. You are not giving up on your cat. You are protecting them from suffering.
If you're going through this and finding it hard, please reach out for support — whether to your vet, a trusted friend, or a pet loss support organisation. What you're carrying is real, and you don't have to carry it alone.
Support Is There
If you're going through this and finding it hard, please reach out for support. Losing a cat — or facing the possibility of it — is a genuine grief, and you deserve to be heard.
In the UK, two free, confidential helplines are available:
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Blue Cross Pet Loss Support — 0800 096 6606, open every day 8.30am–8.30pm, also available via webchat and email at plsmail@bluecross.org.uk
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Cats Protection Paws to Listen — 0800 024 9494, open Monday to Friday 9am–5pm, staffed by trained volunteer listeners who specialise in cat-related grief
In Australia, Griefline offers free national grief support including pet loss — 1300 845 745, open 8am–8pm daily.
In the USA, the Association for Pet Loss and Bereavement (APLB) at aplb.org offers free online support, chat rooms, and resources for those grieving a pet.
You are not giving up on your cat by asking for help for yourself. What you're carrying is real, and you don't have to carry it alone.
Want to go deeper?
If you're facing the loss of your cat, Marina has written a book to help you through it — Losing Your Cat is available in the Digital Cattery alongside our full range of cat care guides and books.