Cancer in Cats: Understanding Types, Diagnosis, and Treatment

Advances in feline oncology offer new hope for earlier detection and personalized care.

By Medha deb

Created on Sep 2, 2025

Advances in feline oncology offer new hope for earlier detection and personalized care.

Feline cancer is an emotionally challenging but increasingly common health issue faced by cats and their caregivers. While a cancer diagnosis can be devastating, advances in veterinary medicine offer hope for improved treatment and quality of life. This guide outlines the symptoms, common types, diagnostic methods, and treatments for cancer in cats, empowering owners to make informed decisions for their companions.

What Is Cancer?

Cancer is a broad term describing diseases caused by the uncontrolled growth and spread of abnormal cells in the body. These cells may form a mass known as a tumor. Not all tumors are cancerous (benign), but malignant tumors can invade nearby tissues and spread (metastasize) to other parts of the body.

Benign tumors: Usually do not spread or invade surrounding tissue. Treatment may still be required if the tumor impairs normal function.
Malignant tumors (cancer): Can infiltrate adjacent tissues and disseminate to distant sites through the bloodstream or lymphatic system.

Cancer can develop in virtually any organ or tissue, from the skin to internal organs such as the liver, intestines, or lungs.

Cancer in Cats: How Common Is It?

Cancer is more frequently diagnosed in older cats, but can occur at any age. Thanks to better veterinary care and early detection, more cats are now diagnosed and treated for various tumor types. The exact prevalence is not well established, but cancer is recognized as a major cause of illness and death in feline populations.

Causes and Risk Factors of Feline Cancer

The precise causes of cancer in cats are not always identifiable, but it often arises from a combination of genetic, environmental, and lifestyle factors. Some known risk factors include:

Age: Older cats are at higher risk.
Breed: Certain purebred cats may be predisposed to specific cancers.
Viruses: Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) increase the risk of lymphoma and other cancers.
Exposure to sunlight: Increases the risk of skin cancers, especially in light-colored cats.
Reproductive status: Intact (unspayed) female cats are at higher risk for mammary tumors.
Chronic inflammation: Ongoing inflammation (such as at injection sites) can occasionally lead to tumor development.

Common Types of Cancer in Cats

Cancer in cats can develop in almost any part of the body. Some types occur more frequently than others. Understanding the different forms can help in recognizing early warning signs and seeking prompt treatment.

Cancer Type	Description	Key Symptoms
Lymphoma	The most common cancer in cats, affecting lymphoid tissues (lymph nodes, intestines, kidneys, etc.).	Weight loss, appetite loss, vomiting, diarrhea, lethargy
Mammary Tumors	Cancer of the mammary (breast) glands. Most tumors in cats are malignant.	Firm mass under the skin, swelling near nipples, discharge, ulceration
Squamous Cell Carcinoma	A common skin and oral cancer related to sun exposure or affecting the mouth.	Sores that donât heal, swelling, ulceration, drooling, facial swelling, difficulty eating
Fibrosarcoma	Tumor of soft tissues or connective tissue, often locally invasive and sometimes associated with injection sites.	Firm mass under the skin, swelling, sometimes at previous injection sites
Mast Cell Tumors	Arise from immune cells in the skin or spleen, may be benign or malignant.	Skin lumps, ulceration, digestive symptoms if spleen/intestines involved
Osteosarcoma	Aggressive bone cancer, rare in cats but serious when present.	Pain, swelling, limping, sometimes pathological fractures

Lymphoma

Lymphoma is the most frequently diagnosed cancer in cats. It often affects the intestines (as “intestinal lymphoma”), lymph nodes, and sometimes organs like the kidneys or nasal passages. The disease is strongly linked to infections with FeLV or FIV.

Mammary Tumors

Mammary (breast) tumors are common in older, unspayed female cats. Up to 90% are malignant, with the risk significantly reduced by spaying before 6 months of age. These tumors can spread quickly to lymph nodes and lungs if not detected and treated early.

Squamous Cell Carcinoma (SCC)

This locally invasive cancer often affects the skin (ears, nose, eyelids) and oral cavity. In white or pale-skinned cats, sun exposure greatly increases the risk. Non-healing sores or ulcers that fail to resolve should raise concern for SCC.

Fibrosarcoma

Fibrosarcoma occurs in the connective tissues and is known for local aggression. Rarely, it can develop at vaccination or injection sites (injection-site sarcomas). The tumor typically presents as a firm lump, sometimes growing rapidly.

Other Tumors

Mast Cell Tumors: Can appear as lumps on the skin or affect internal organs like the spleen, varying in behavior from benign to malignant.
Osteosarcoma: Although rare in cats, this bone cancer is aggressive and most often involves the limbs or jaw.
Lung, liver, and intestinal tumors: Less common, often present with signs related to organ dysfunction.

Symptoms of Cancer in Cats

The signs of cancer depend on its type, location, and stage. Many symptoms are subtle or overlap with other illnesses. Owners should be alert to the following changes:

Persistent lumps or swellings
Non-healing sores or ulcers
Sudden weight loss
Loss of appetite
Lethargy and decreased activity
Unexplained bleeding or discharge
Pain or sensitivity in a specific area
Difficulty eating or swallowing
Changes in bathroom habits (urination or defecation)
Persistent lameness or stiffness

Any persistent or progressive symptom in your cat should prompt a veterinary evaluation, even if cancer is not initially suspected.

Diagnosis: How Is Cancer in Cats Diagnosed?

Diagnosis of cancer in cats involves a combination of history, physical examination, laboratory testing, and diagnostic imaging. To confirm cancer and guide treatment, your veterinarian may recommend:

Physical examination: Palpation of lumps, assessment of overall health, and search for additional abnormalities.
Blood tests: Check organ function, blood cell counts, and look for factors that may complicate anesthesia or treatment.
Imaging: X-rays and ultrasound are commonly used to assess the location, size, and spread of tumors.
Fine needle aspirate or biopsy: Extraction of cells or tissue to be examined under a microscope. A biopsy is essential to determine the specific type of tumor and its malignancy grade.

For cancers suspected of spreading (metastasis), advanced imaging such as CT or MRI may be recommended.

Staging and Grading Cancer

Once cancer is confirmed, it is important to establish:

Stage: How far the cancer has spread (localized vs. metastatic).
Grade: How abnormal the cancerous cells are compared to normal tissue. High-grade tumors tend to be more aggressive.

Staging helps guide treatment choices and prognosis, while grading indicates the likely behavior of the tumor.

Treatment Options for Cancer in Cats

The most effective treatment varies depending on the type, location, and extent of the tumor, as well as the catâs overall health and owner preferences. Veterinary oncologists may recommend one or more of the following:

Surgery
Chemotherapy (anti-cancer drugs)
Radiotherapy (radiation therapy)
Palliative care and supportive therapies

Surgery

Surgery is the mainstay of treatment for many localized tumors and is most likely to result in a cure if the entire tumor (with margins of healthy tissue) can be removed. Complete surgical removal is not always possible, especially in difficult locations or advanced cancers. Sometimes, surgery is performed to reduce tumor size (debulking) and improve quality of life or to assist other therapies.

Chemotherapy

Chemotherapy uses drugs to kill rapidly dividing cancer cells. It is primarily indicated for cancers that are systemic (like lymphoma) or in cases where surgery alone is not curative. Chemotherapy in cats is generally well-tolerated, with less aggressive dosing than in humans, so severe side effects are less common.

Radiotherapy

Radiotherapy involves delivering concentrated beams of radiation to the tumor, usually under anesthesia or sedation. This modality is typically used for tumors that are inaccessible to surgery or after incomplete surgical removal. Sessions are given over several weeks and aim to kill cancer cells with minimal damage to healthy tissue.

Palliative and Supportive Care

When cure is not possible or treatment risks outweigh benefits, palliative care focuses on comfort and quality of life through pain management, anti-inflammatory medication, nutritional support, and symptom relief. For some advanced cancers, palliative care is a compassionate decision.

Prognosis and Life Expectancy

Prognosis depends on:

The type of cancer
The stage and grade at diagnosis
The general health of the cat
The feasibility of curative treatment

Some cancers can be cured or managed for extended periods with early detection and aggressive therapy. Others may progress rapidly, especially if diagnosed late. Your veterinarian or veterinary oncologist can provide the most accurate prognosis based on each individual case.

Living With a Cat Diagnosed With Cancer

Caring for a cat with cancer is demanding both emotionally and practically. Here are some tips to support your cat:

Keep up with regular veterinary appointments and monitor for changes.
Ensure a comfortable, low-stress home environment.
Provide palatable nutrition and adequate hydration.
Administer medications as prescribed and monitor for side effects.
Communicate openly with your vet about your catâs comfort and any questions or concerns.

Remember, the goal is to maximize quality of life for whatever time remains, whether pursuing aggressive therapy or focusing on palliative care.

Prevention and Early Detection

Have your cat neutered or spayed at the appropriate age to reduce the risk of certain reproductive cancers.
Limit sun exposure for white or light-colored cats to prevent skin cancer.
Keep your cat up to date on vaccinations (such as for FeLV) and have regular health checks.
Monitor your catâs health and report any persistent lumps, sores, or other warning signs promptly.

Frequently Asked Questions (FAQs)

Q: What are the most common cancers in cats?

A: The most common feline cancers include lymphoma, mammary (breast) tumors, squamous cell carcinoma, fibrosarcoma, and mast cell tumors.

Q: What should I do if I find a lump on my cat?

A: Any new or growing lump should be checked by a veterinarian, as early examination and biopsy improve treatment options and outcomes.

Q: Can cancer in cats be cured?

A: Some cancers, particularly if caught early and surgically removed, can be cured. Others are managed to improve quality of life or extend survival time.

Q: Is chemotherapy safe for cats?

A: Yes, chemotherapy in cats is generally safe and well-tolerated. Side effects are usually mild compared to humans, as lower doses are used to prioritize quality of life.

Q: Does early spaying reduce cancer risk?

A: Yes. Spaying a female cat before her first heat cycle dramatically reduces the risk of mammary cancer.

Q: What is palliative care in feline cancer?

A: Palliative care focuses on maximizing comfort and managing symptoms when curative therapy is not possible, emphasizing quality of life over disease eradication.

Q: How can I help my cat during cancer treatment?

A: Provide supportive home care, follow veterinary advice closely, allow your cat to rest, ensure high-quality nutrition, and address pain promptly.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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