Help! What Are They Talking About? (Part 1)

A cancer diagnosis in a pet, family member, or friend is typically overwhelming. We can become crippled by "worst case scenario" thinking as well as feelings of fear and anxiety. These feelings are normal, but they do nothing to help us to determine the best course of action or to ensure that our loved one receives the best treatment.

In order to decrease overwhelm and allow you to make the most educated decisions, you need to know what the oncologist (medical or veterinary) is actually talking about. Does your mind go blank when they use terms such as "histopath", "margins", "metastasis", "radiation", or "neoplasia"? If the answer is 'yes', you're not alone; read the next few articles in this series and you'll have these answers. If the answer is 'no', keep reading; I see many clients that have an inaccurate understanding of these terms.

Over the next few weeks, we're going to define some of the more common terms used in oncology, so you'll have a better understanding of cancer-related terms and can subsequently have a more educated discussion with a healthcare provider. Cancer is incredibly common in both people and in dogs - an understanding of these terms is essential for everyone. If we live long enough, we're all going to have a human or animal loved one develop cancer - be the best help you can be by already having an understanding of the basics.

Part 1 -

(1) Tumor:

A mass of tissue caused by an abnormal growth of cells, which can be benign (not cancer) or malignant (cancer). Also called neoplasia.

(2) Cancer:

A group of diseases characterized by uncontrolled cell growth and the potential for both invasion of the abnormal cells into surrounding tissues and the spread of these cells to organs throughout the body.

(3) Neoplasia:

A mass of tissue caused by an abnormal growth of cells, which can be benign (not cancer) or malignant (cancer). Also called a tumor.

(4) Metastasis:

The spread of neoplastic cells from a primary tumor (the primary tumor is where cancer started) to secondary (or tertiary, etc.) sites, where the cells multiply to form a mass.

The process by which a cell is able to leave the primary tumor, travel elsewhere in the body and survive involves an in-depth step-by-step process, which I will address in a future article.

Each type of malignant tumor (ex. anal sac adenocarcinoma, osteosarcoma, mast cell tumor) has its own pattern of metastasis. Some tumor cells travel by blood vessels and others by lymphatics. Knowing this pattern helps the oncologist know where to look for evidence of metastasis. In some cases, we have to assess local lymph nodes, in other cases, we have to assess the lungs, etc. Every case is different.

(5) Benign:

Benign tumors can arise in any tissue of the body and are characterized by local growth only. This means that they are only able to form a space-occupying mass that places pressure on surrounding organs and tissues, but the cells of benign tumors cannot spread to distant areas of the body (they cannot metastasize).

If a tumor is benign, treatment is focused on local control only, which usually involves surgery.

(6) Malignant:

Malignant tumors can arise in any tissue of the body. The cells of these tumors have the ability to travel to distant organs throughout the body (called metastasis).

In many cases, in order to treat a malignant tumor and prolong survival in a patient for as long as possible, treatment must focus on (a) removal/killing of all primary tumor cells, (b) and delaying metastasis using chemotherapy.

Sometimes we're successful in removing all primary tumor cells (the primary tumor is where cancer started) with a single surgery. In other cases, surgery will leave a few cells behind. To prevent those cells from forming a new tumor, treatment with radiation or electrochemotherapy is often recommended.

Dr. Lori Cesario

Board Certified Veterinary Oncologist

A few other articles you might enjoy...

(1) Dog Breeds and Their Associated Cancers

(2) Mast Cell Tumors - The Great Imitator in Canine Cancer

(3) Canine Splenic Tumors - What You Need To Know

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