Oncologists treat cancers. Cancers generally mean that the wrong sort of cell is growing in the wrong place. The technical term is ‘neoplasia’ which literally translates as ‘new growth’. Neoplasia can be benign (does not grow into surrounding tissue or spread around the body) or malignant (can grow into surrounding tissue and/or spread around the body). Some of the most common sorts of cancers in cats are very treatable conditions. Many skin lumps and bumps can be cancers (benign or malignant). Hyperthyroidism is usually caused by benign growth of the thyroid gland (in the neck) that causes too much thyroid hormone. This is one of the most treatable diseases of cats and there are several good treatment options. Lymph cell cancers tend to be very common in cats and (depending on their location) can be very controlled or even fully treated with chemotherapy.