Treating Tumors and Cancer in Cats

The best possible treatment option is surgical removal of a cancer that has not spread. To prevent recurrence, a surrounding margin of normal tissue should also be removed. An initial approach that removes the tumor with an adequate margin of normal tissue may be the most important factor in controlling cancer. When a cancer recurs locally because of incomplete excision, the opportunity for cure is often lost. That's why surgeons speak of “clean margins,” meaning no cancer cells are found on the edges of the surgical excision.

A cancer that spreads only to local lymph nodes may still be cured if all the involved nodes can be removed along with the primary tumor. Even when a cancer is widespread, removing a bleeding or infected mass, or simply a large one that is interfering with a normal physical function, can provide relief and temporarily improve the quality of life.

Electrocautery and cryosurgery are two techniques by which tumors on the surface of the body can be removed. Electrocautery means burning off the tumor using electricity; cryosurgery involves freezing the tumor to remove it. These methods provide an alternative to surgical removal and are suitable for benign tumors. New surgery techniques may use lasers or hyperthermy-heat treatment.

Radiation therapy is useful in managing some surface tumors and deeply situated tumors that cannot be controlled by surgery. Cures are possible. A potential disadvantage of radiation therapy is that it requires special equipment and must be done at a medical center. Radiation therapy can also be done to relieve pain, especially with very painful cancers such as osteosarcoma (bone cancer).

Chemotherapy uses anticancer drugs given at prescribed intervals. These drugs, even when tightly controlled, have major side effects. Still, they are useful in managing some widely spread cancers. The development of new chemotherapy agents will lead to higher success with less side effects. In humans, chemotherapy is aimed at achieving a cure. In cats, chemotherapy is aimed at controlling the disease and giving the cat a period of remission.

Pain medications and nutritional management are now also important parts of cancer therapy. Nutritionally, cancerous cells seem to do well on carbohydrates and not so well on fat. Adding omega-3 fatty acids (think fish oils) to the diet may be helpful, as may adding the amino acid arginine. Although much of this work has been done primarily with dogs, it should apply to cats as well. The use of additional antioxidants is under discussion at this time.

Cancer Treatments

  • Surgery - Surgery can completely remove a cancer or make it smaller so that chemotherapy and radiation are more effective. Risks include anesthesia, bleeding problems, and postoperative pain. Cures are possible with certain cancers and early intervention.
  • Chemotherapy - Chemotherapy uses drugs to try to kill the cancer cells with the least amount of damage to normal cells. Side effects can include nausea, lowered immunity, and bleeding problems. Cats don't usually experience major hair loss. Not all cancers are susceptible to chemotherapy.
  • Radiation -Radiation uses specially calibrated X-rays to damage cancer tissues with the least amount of damage possible to normal
    tissues. Side effects include tissue sloughing, lowered immunity, and damage to normal tissue. Anesthesia is required. This treatment is only available at veterinary referral centers. Not all cancers are susceptible to radiation and the location of the cancer may make this impossible.
  • Cryotherapy - Cryotherapy uses probes to freeze cancerous tissues. The goal is to destroy the cancer with the least damage to surrounding normal tissues. This is only available at veterinary referral centers. Not all cancers are susceptible to cryotherapy, and the location of the cancer may make this therapy impossible.
  • Hyperthermy - Hyperthermy uses heat probes or radiation to destroy cancerous tissues by overheating them. The goal is to destroy the cancer with the least damage to surrounding normal tissues. This is only available at veterinary referral centers. Not all cancers are susceptible to heat damage. The location of the cancer may make this therapy impossible.
  • Diet - Diet has been shown to be helpful in controlling cancer. The goal is a diet with limited simple sugars, moderate amounts of complex sugars such as carbohydrates, highly digestible protein in moderate amounts, and set amounts of certain types of fats. These dietary guidelines tend to “starve” the cancer cells and help the normal cells stay healthy.
  • Immunotherapy - Immunotherapy uses immune reactions to fight off the cancer cells. This method may use a nonspecific immune modifier such as interferon, or vaccines specifically tailored to the cancer of the individual. Much of this work is experimental but shows great promise.

This article is excerpted from “Cat Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.