The most common form of hepatocellular carcinoma is the development of one large mass on one lobe of the liver. Tumors can also develop in a nodular manner on multiple lobes of the organ. In rare cases, tumors will form all through the liver tissue, an occurrence referred to as “diffuse growth”. The left lobe of the liver is most commonly affected and is also the easiest to treat. This type of cancer is found slightly more often in male cats, and in cats over the age of nine. While the liver generally detoxifies substances in the body, it seems that certain chemicals may actually become more toxic after interacting with the liver, and cancer then forms. Hypoglycemia (low blood sugar) is a health issue that often occurs secondary to hepatocellular carcinoma.

Most cancers that develop in a cat's liver have spread from other organs and ended up in the liver due to its filtration of the bloodstream. This is not the case with hepatocellular carcinoma. This cancer actually stems directly from the liver cells, called “hepatocytes”. It is a fairly common type of cancer in cats that creates tumors in and on the liver. Generally, hepatocellular carcinoma has a low likelihood of metastasizing to other body parts. If it does spread, it often will appear in the lungs or the spleen. 

Cats with this type of cancer may not exhibit any symptoms until progression is severe. Once symptoms begin to manifest, they rarely are obviously linked to the function of the liver. All signs to watch for are listed as follows:

The exact cause of hepatocellular carcinoma is largely unknown. It is thought that both genetic makeup and the liver’s processing function may both contribute to the mutating of cells. Possible causes are listed below.

In cats that are not showing symptoms, liver cancer may be discovered by a vet addressing fluid accumulation in the abdominal cavity. If you have brought your cat to the veterinary clinic due to concern over symptoms, be sure to provide the veterinarian with the cat's full medical history. A complete physical examination will then be performed, with focus on the abdomen to feel for masses in the liver area. Full blood work will be run including a complete blood count, which will reveal anemia if the cat is suffering from hepatocellular carcinoma. The biochemical profile may show elevated liver enzymes. A coagulation panel should also be run, gauging the cat's ability to clot blood. Urinalysis will also reveal how the liver is functioning.

X-rays of the abdomen will be needed to identify and locate the mass or masses on the liver. A chest x-ray may also be requested to monitor the lungs for any metastasis of the cancer. A CT scan or MRI can give a more detailed, three-dimensional view of the growths and help with surgical planning. The cat should be tested to verify that it is able to survive anesthesia. At this point, you may be referred to a veterinary surgeon with experience in liver tumor excision. A tissue sample biopsy will need to be taken and sent for histopathological examination to confirm the cancer type. If fluid is present in the liver, a portion of it may be removed with a syringe and microscopically evaluated to see if cell changes are noted. All of these tests will be done to differentiate hepatocellular carcinoma from other diseases and cancers of the liver.

Once a diagnosis of hepatocellular carcinoma has been made, prompt treatment is necessary to decrease the chance of the cancer spreading to other organs. Depending on the cat's condition, supportive care may be needed throughout this time, and stabilization may be required before treatments can be started.

The most effective treatment against this cancer is the removal of tumors present, if possible. Singular masses are the easiest to excise. Even if the tumors are diffuse, up to 80% of the liver can be removed, allowing a great amount of cancerous tissue to be taken out. An incision is made into the abdomen to reveal both the liver and the growths. A surgical stapler or a scalpel may be used for the removal. General anesthesia is required for the procedure.

To rid the body of the cancer on a microscopic level, chemotherapy is often paired with a surgical removal of cancerous tumors. Administration of powerful medication will be needed over a longer period of time to stop cancer growth.

Sometimes paired with chemotherapy, injecting glue into the blood vessels that supply the liver tumor(s) can block blood from reaching the growths and potentially shrink them. 

Cats who have undergone surgery of the liver will require attentive at-home care. The incision site will have to be monitored daily to ensure that it is clean and free of infection. An Elizabethan collar may be necessary to prevent the cat from chewing or licking at its incision. Painkillers and other medications will need to be given as prescribed during this time. Activity should be limited until the incision has healed. Approximately two weeks after the surgery, a follow-up appointment will be needed to assess how the cat is healing and to start administering chemotherapy If needed.

A good prognosis is expected in simple, singular mass cases that have been detected early. If the cat properly recovers from surgery, life expectancy can be lengthened by years. If the cancer has progressed or has metastasized to other body parts, the prognosis worsens. It should be noted that hepatocellular carcinoma only spreads in less than five percent of diagnosed instances. Nodular or diffuse tumor growth also negatively affects the long term outlook. Feeding your cat a high quality, species-appropriate diet can aid management of liver cancer.