By Patricia Long
Like any area of study, cancer has its own vocabulary, which can be very confusing. Decisions surrounding management of a beloved pet affected by a debilitating and life-threatening disease can be very difficult. Learning to understand what veterinarians are saying and doing to assist a dog with cancer is a benefit to dog owners whose intensions are to save or improve their dog's quality and length of life.
This document presents an overview of cancer. The information is offered to clarify terms associated with cancer and outlines steps involved in the entire cancer management and disease treatment process.
WHAT IS CANCER?
Cancer is caused when cells begin to grow out of control, become abnormal, and lack the genetic agent that causes them to die.
- A neoplasm (new growth) is tissue that wasn't there before: in cancer - a lump, a tumor.
A tumor, which is an abnormal mass of cells, can be either benign or malignant.
A benign (good) growth does not invade surrounding tissue, and it does not spread to other parts of the body - it is not cancer. (However, as with the example of fibroid uterine tumors, benign tumors can cause problems severe enough that they need to be removed.)
A malignancy (mal = bad), which does invade and can spread, is cancer.
GENERAL TYPES OF CANCER
- oma, suffix used when a tumor is malignant.
- sarcoma, cancer of the bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. (fibro - fibrous connective tissue; hemangio - blood vessels, soft tissue; osteo - bone)
- lymphoma, cancer of the lymphatic system (used in vet medicine interchangeably with lymphosarcoma)
- melinoma, a form of skin cancer.
- carcinoma, cancer in the skin or in tissues that line or cover internal organs.
♦ PREVENTION ♦
Feed healthy foods, provide good exercise and a nurturing, low-stress environment - that's about all you can do. However, it's an important part!
♦ DETECTION ♦
(Early detection of cancer helps to increase survival.)
From the American Veterinary Medical Association:
Ten Common Signs of Cancer in Small Animals
1. Abnormal swellings that persist or continue to grow
2. Sores that do not heal
3. [unexplained] Weight loss
4. Loss of appetite
5. Bleeding or discharge from any body opening
6. Offensive odor
7. Difficulty eating or swallowing
8. Hesitation to exercise or loss of stamina
9. Persistent lameness or stiffness
10. Difficulty breathing, urinating, or defecating
♦ DIAGNOSIS ♦
The size and location of the growth will help to determine the methods that can be used.
Some of the tools that are used can include a physical examination, an x-ray, MRI, CAT Scan, a blood test, a fine needle aspirate to draw out some of the affected cells for testing, a biopsy to surgically remove some of the affected tissue.
♦ GENERAL INFORMATION ON BIOPSIES ♦
When a surgical biopsy is performed, some of the tumors may be removed completely at that time.
The surgeon may attempt to remove the entire growth and also to remove enough of the surrounding tissue to make sure all the cancerous cells have been eliminated.
Cross sections will be made of the tissue removed for examination under a microscope by a pathologist.
The pathologist will attempt to determine several things.
What type of growth is it, benign or malignant?
What is the origin of the cellular structure (from what organ)?
Are the cells well differentiated? What is the significance of well differentiated cells?
What is the grade of the tumor? What is the stage of the disease?
Did any tumor cells appear at the edges of the sample indicating some may have been left behind during surgery?
Or did the edges of the sample have "clean margins" with normal cells appearing at all edges?
♦ ABOUT CANCER CELLS - Grading & Staging ♦
Cell structure is very well defined: there is a surrounding cell membrane and a nucleus, a bit like an egg without the shell.
As cancer cells grow out of control, this structure breaks down, and often becomes an amorphous (no definite form, shapeless) mass with lots of nuclei and very few distinct cell membranes.
This is called an anaplastic tumor (ana - backward, plasia - growth), and is not differentiated enough to even determine the type of cancer cells present.
The anaplastic tumors are very aggressive, fast growing cancers.
Grading is done based on how well differentiated (the cells are immature and don't look much like the normal cells in the originating tissue) the cell structure appears, and helps to predict how aggressive the cancer may be.
Staging is a method used to indicate how far the cancer may have spread. The spread of tumors to other sites is called metastisis (change).
The staging system is used to divide cancers into categories to help classify the extent of the disease. These categories vary from cancer to cancer.
This classification helps to determine possible treatment options, follow up, and supportive care.
In the lowest stage, the cancer is self-contained and hasn't spread to any surrounding tissue.
The next stage may still have the single site tumor but also may have lymph node involvement indicating that it has begun to spread.
The next stage may have multiple tumor sites with no lymph node involvement, and the highest level might be multiple tumors in multiple sites with other organ involvement.
♦ PROGNOSIS ♦
The prognosis will help you to start determining the course of action.
Prognosis is an imperfect art at best. Prognosis is the prediction of the likely course of the disease, the chance for recovery or recurrence.
Prognosis will be based on literature studying many similar cases, as well as the veterinarian's experience.
The prognosis will vary from cancer to cancer, from breed to breed, from dog to dog, and from treatment to treatment.
♦ CONSIDERATIONS FOR TREATMENT ♦
Many things must be considered when planning any treatment.
• What is the overall health of the dog?
• The age of the dog?
• How aggressive is the cancer?
• What is the probability of remission, either temporary or complete?
• What is the possible extension of life that can be reasonably expected?
• What are the side effects, or risks, to the dog associated with each treatment option?
• What is the impact to the family in terms of supportive care?
• What is the cost?
• How accessible is the treatment?
• How stressful are vet visits for the dog?
There is not an answer that is 'right' for all patients or patients' families, and the decision is never easy.
The goal of any treatment should be to improve the chances for quantity and quality of life, as long a quality life as is possible.
♦ TYPES OF TREATMENT FOR CANCERS ♦
Treatments continue to expand as researchers identify new therapies to fight cancer. Please consult with your dog's veterinarian for options and specific current information on therapies and treatments.
Some dogs and some cancers respond well to treatments and supportive care which results in short or long term extension of a good quality of life for the dog. Talking with your dog's breeder and learning about other owner's experiences coping with cancer can be beneficial.
- Surgical excision is one type of treatment.
This is not always possible if the growth has invaded surrounding tissue, has spread too far to remove the surrounding tissue, or is in an organ that can't be surgically reduced (heart, brain, spine, etc) without severe risk or complications.
- Chemotherapy uses drugs to reduce or eliminate cancer.
This is usually an adjuvant therapy, or one that is used after the primary therapy of surgical excision.
The drugs used will be those that have been found to be effective in killing the cancer cells.
Cancer cells grow rapidly, and drugs that target rapidly growing cells may also damage the healthy cells that normally grow rapidly, such as the cells in the GI tract or hair.
The normal cells will repair themselves after the drugs are gone.
- Radiation therapy uses energy to target specific cells in order to destroy them.
This is usually also an adjuvant therapy, and is often used in combination with chemotherapy.
X-rays are the most common form of this therapy.
Radioactive implants are used for some forms of human cancers, and research is ongoing to find other effective means of targeting the specific cells to receive the radiation energy.
- Homeopathic treatments...
can help to support the body's own defense system.
Supplements can target specific organs and the immune system.
These are becoming more accepted by the traditional veterinary community, and are often used in conjunction with the traditional therapies, or instead of traditional therapies - especially for cancers that do not respond to the traditional therapies.
- Biological therapies, or immunotherapy...
use the body's immune system to fight the cancer.
Using substances to boost or suppress the general immune system, to help the immune system target the cancer itself, to use the tumor to create a vaccine to help boost immunity, to stimulate bone marrow production of white blood cells - these are all various forms of immunotherapies.
Terms used: immunomodulating agents, biological response modifiers, interferons, interleukins, colony-stimulating factors, monoclonal antibodies.
- Angiogenesis inhibitors...
are used in cancer treatment.
These substances inhibit, or prevent the formation and proliferation of blood vessels that are necessary to feed a tumor.
Cancer cannot grow without the development of supporting blood vessels.
The BMDCA's Health Committee can not diagnose or advise you on specfic case cancer management protocols.
If you suspect or know your Berner has cancer, please rely on your veterinarian's recommendations.
We encourage you to share experiences with the Berner community...
Various cancer Research Studies are supported by the BMDCA and the Bernese fancy. Please consider participating.
Submit your dog's information to Berner-Garde...
• BG's individual dog submission form
• Bernese Mountain Dog DNA/Tissue Repository
Also see the • Berner-Garde database "Reports" section to search for additional data pertaining to incidence of cancer in Bernese Mountain Dogs.