Feline Mammary Cancer

Cats get mammary (breast) cancer same as humans and dogs. Just like in humans and dogs, mammary cancer in cats is a potentially fatal disease. In many cases, it can be prevented. It has been shown that simply by spaying a cat when she is under 1 year of age decreases that cat's chance of ever getting mammary cancer by 86%. What this means is that spaying a cat when she is young not only helps aid feline population control, but it will also help the cat live longer by preventing this bad disease.

If a cat develops mammary cancer, it can still survive. The number one parameter which influences the survival of the patient is the size of the cancer when first found and surgically removed. If only 1 nodule of cancer is present and if it is less than 2 cm. in size, then immediate removal of the cancer will often result in cure. However, if the cancerous growth is over 3 cm. in size, then most of these cats will eventually succumb to the disease.

If a mammary tumor is found on a cat, then I recommend its immediate removal after a thorough work up. If the tumor is small, then I let the client know that a cure is highly likely. If the tumor is greater than 3cm. in size, then I let the client know that cure is less likely but is still a possibility. Prior to tumor removal, I do whole body radiographs to check for tumors elsewhere in the cat, such as the lungs. Sometimes, I will ultrasound the abdomen if I feel that spread to the lymph nodes in the abdomen is a possibility. If cancer tissue is found elsewhere, I do not recommend surgical removal of the mammary cancer. However, I can sometimes shrink the cancer for months with chemotherapy and that option is given for those cats. In those cases in which the cancer only appears to be on the mammary gland, then I recommend removal as soon as possible.

Once the tumor is removed, it is forwarded to a veterinary pathologist. The pathologist will let me know how aggressive the tumor cells appeared and whether or not it had likely spread. If the pathologist felt that I had gotten the entire tumor through my surgical excision and it was unlikely to have spread anywhere else, then no further treatment is recommended. On the other hand, if it looked like the tumor was spreading elsewhere (a more likely scenario in those cases in which the tumor is not less than 2cm. in size) then I recommend follow up chemotherapy in those cases.

The bottom line for a cat owner is to get his/her cat spayed young...certainly at less than a year of age. At my veterinary hospital it is recommend that cats are spayed at 5-6 months of age although for some humane organizations we have spayed cats as young as 7 weeks old with no problems resulting. In addition, if you have a cat that was not spayed young, check it weekly for mammary masses. If one is felt, take it to your veterinarian as soon as possible. Removing the lump or mass when it is small could be life-saving.