If your cat is not eating, is lethargic, or is experiencing side effects like sedation or decreased appetite, these could be signs that your cat is suffering from the treatment. It's important to report these symptoms to your veterinarian so adjustments can be made.

Currently, there's no preventative medicine for cancer in cats. While early detection and genetic screening are available in humans, these are not yet common in veterinary medicine.

Without treatment, the lifespan of a cat with cancer could be as short as weeks or days, particularly if it's a rapidly growing type of cancer. Changes in behavior such as hiding, lethargy, decreased appetite, or changes in usual habits are indicators of a decline in health.

The lifespan of a cat with cancer after treatment varies based on the type of cancer. Cats with GI lymphoma can live for a long time with chronic medication. If it's a cancer of the mouth, the lifespan can range from months to years, depending on the detection stage. Every cat will have a different response to treatment.

Some types of cat cancers can be cured, especially if it's a growth that can be removed. However, other types, such as gastrointestinal lymphoma, can be kept in remission with medication, but it's not a permanent solution. The prognosis will depend on the specific type of cancer, the stage, and if it has spread.