What are neoplasia, tumors and cancer?
Neoplasia is the uncontrolled, abnormal growth of cells or tissues in the body, and the abnormal growth itself is called a neoplasm or tumor. It can be benign or malignant. Benign neoplasms tend to grow slowly; displace, but do not tend to invade, the surrounding body tissues; and do not spread throughout the body. Malignant neoplasms, on the other hand, can be unpredictable and grow at various rates (sometimes rapidly), invade the tissues around them, and spread, or metastasize, to other parts of the body.
The word “tumor” or “mass” is often used to describe the actual swelling or other physical appearance of a neoplasm. The word “cancer” is often confused with neoplasia, but only malignant neoplasms are truly cancers.
How common are neoplasia and cancer?
Approximately 1 in 4 dogs will, at some stage in their life, develop neoplasia. Almost half of dogs over the age of 10 will develop cancer. Dogs get cancer at roughly the same rate as humans, while there is less information about the rate of cancer in cats. Some cancers, such as lymphoma, are more common in cats than in dogs.
Approximately 1 in 4 dogs will, at some stage in their life, develop neoplasia.
Neoplasia is often suspected on the basis of the pet’s medical history and physical exam. Additional tests, such as radiographs (x-rays), blood tests, and ultrasound exams, may be necessary to confirm neoplasia.
For most tumors, cytology (withdrawing some cells from a mass to examine under a microscope) can quickly provide basic information about the tumor type, and can confirm a diagnosis for certain types of cancer. For many tumors, a biopsy – taking a tissue sample from the neoplasm for examination under a microscope – is often necessary to confirm the diagnosis and help determine if the neoplasm is benign or malignant. Additional cytology or biopsies of other tissues, such as lymph nodes, may be necessary to determine how far a malignant neoplasm (cancer) has spread.
Advanced imaging such as computed tomography (CT) scan, magnetic resonance imaging (MRI), or positron emission tomography (PET) scan can also improve the understanding of the tumor’s location and possible treatment options.
Oncology is a growing specialty area of veterinary care. Oncologists are veterinarians who have obtained additional training beyond veterinary school and are certified by the American College of Veterinary Internal Medicine (ACVIM) in oncology. They work together with your veterinarian to provide the best care for your pet with neoplasia.
Unfortunately, the cause of most neoplastic diseases is not known and, therefore, prevention is difficult. There is evidence that secondhand smoke increases the risk of some cancers in dogs and cats.
Spaying reduces the risk of mammary cancer in dogs. Half of all breast neoplasms in dogs and greater than 85% of all breast neoplasms in cats are malignant, and spaying female pets before 12 months of age reduces this risk. Neutering eliminates the risk of testicular cancer. Conversely, there is evidence that spaying and neutering can increase the risk of certain other cancers. Genetic predisposition to some cancers in certain breeds or breeding lines has also been reported. Talk to your veterinarian about the benefits, risks, and timing of spaying or neutering your pet.
Early detection and treatment are the best ways to manage neoplasia in pets.
The human-animal bond is stronger than you might think. In fact, the study of cancer in pet animals is shaping our understanding of cancers in people and leading to additional treatment options. According to a 2007 article by Philip J. Bergman, DVM, MS, PhD, DACVIM (Oncology) and Jeffrey Toll, VMD, DACVIM, the spontaneous cancers of pets treated by veterinary oncologists are similar to those arising in people. Dogs and humans are the only two species that naturally develop lethal prostate cancers. The type of breast cancer that affects dogs spreads to bones – just as it does in women. And the most frequent bone cancer of dogs, osteosarcoma, is the same cancer that strikes teenagers.
Dogs are affected by more forms of cancer compared to other companion animals. According to The Veterinary Cancer Society, cancer is the leading cause of death in 47% of dogs, especially dogs over age ten, and 32% of cats. Dogs get cancer at about the same rate as humans, while cats get fewer cancers. Some breeds or families of dogs have a higher incidence for developing cancer at an earlier age, but in most cases it’s a disease found in aging animals. There are nearly 100 types of animal cancer. Cancer in pets can be found in the skin, bones, breast, head & neck, lymph system, abdomen and testicles. Leukemia is the most common type of cancer in cats and lymphoma and mammary gland cancer are the most common type of dog cancers.
Cancer occurs when the body’s immune system cannot stop cells from replicating at an abnormally fast, disorderly pace and forming a mass known as a tumor. Just as in humans, companion animal cancer is not caused by any single factor. While genetics and environmental factors can play a role in the disease’s development, other variables such as toxins, radiation and tumor viruses, as well as hormones can also be responsible for causing several types of cancer. And finally, suppressed or deficient immune systems can increase an animal’s risk of developing cancer.
Approximately one-third of all tumors in dogs are skin tumors, and up to twenty percent of those are mast cell tumors. The most common location to find mast cell tumors is the skin, followed by the spleen, liver, and bone marrow. Approximately half of all skin tumors are found on the body, another forty percent on the limbs (most frequently the hind limbs), and the remainder on the head or neck. Approximately eleven percent occur in more than one location.
Based on these similarities between humans and companion animals, veterinary cancer research benefits both animals and humans with cancer. In fact, The National Cancer Institute’s Center for Cancer Research has instituted a critical Comparative Oncology Program where veterinary oncologists are using naturally occurring cancers in animals to better understand and treat cancer in humans.
Cancer Causes in Dogs and Cats
Family pets are often described as our “best friends” and news that they are sick can be devastating. Cancer is a disease that can affect family pets like dogs and cats. Through the years, research has developed many cures and treatments for use in improving or sustaining the health of pets that present with a cancer diagnosis.
Let’s look at a few of the facts about cancer in family pets. What is it and what can you do about it? Cancer, or a tumor, is typically a mass of tissue that is abnormal. The mass, lump or growth develops when your pet’s cells divide more rapidly than normal.
The mass may also develop because those cells do not die when they ordinarily would. Often we refer to a tumor as benign or malignant. A benign tumor does not spread and does not have the invasive abilities of a malignant tumor. Malignant tumors are known to invade surrounding tissue or set up housekeeping in other parts of your pet’s body.
Cancer is a serious disease in dogs and cats. It is also common. In some areas, cancer is the top cause of death in family pets. Throughout the United States, about fifty-percent of pet dogs and cats lose their life to some form of cancer. The disease is often treatable with surgery, radiation therapy or chemotherapy.
Many pets will do well with surgery to remove the tumor or mass of cancerous cells. Depending on the involved organs and location of the unwelcome cells, surgery may be enough. Veterinarians can recommend that radiation therapy be performed before surgery to shrink the tumor.
Your vet may suggest that chemotherapy should be received by your pet in conjunction with, or independent of, surgery or radiation. Only your veterinarian can recommend the best course of action to treat your pet’s cancer.
Various indicators will lead your veterinarian in making the diagnosis, developing a treatment plan acceptable to you and your pet and performing the necessary treatment.
The Animal Cancer Center at Colorado State University has identified specific information for dog and cat owners about the frequency of cancer and advises pet owners that:
Know the facts and discuss them completely with your veterinarian during development of a treatment plan. Your pet is depending on you and the treatment plan you will create with your veterinarian.