Cancer takes the lives of half of all pets over the age of ten. This terrible disease attacks the body from within. It causes pain and suffering as it gradually drags the animal relentlessly towards death. In order to deal with cancer, we must first understand it.
Cancer is the result of a good cell gone bad. A single, normal cell of any tissue of the body can transform into a seemingly unstoppable, fast-growing, spreading monster. The process starts due to mistakes that are made in the replication of the cell’s DNA (a process called transcription) as that cell divides.
These transcription mistakes, called mutations, can change the functioning of the cell. For example, cells contain genes called tumor suppressor genes that code for “programmed cell death” or apoptosis. Limiting a cell’s lifespan in this way allows for the replacement of old cells with new ones. In cancer cells tumor suppressor genes are turned off and the abnormal cells go right on living. This leads to the accumulation of “immortal” cancerous cells.
The good news is that the body has mechanisms for discovering and eliminating mutations as they happen. The bad news is that this correction mechanism does not always catch every mistake. Since the body contains trillions of cells that are all continuously reproducing, abnormal cells are created all the time. It takes somewhere between 40 and 80 mutations to create a cancer cell.
The body has one more trick up its sleeve to thwart cancer – the immune system. Free-ranging immune cells called natural killer cells, or NK cells, can quickly detect and kill cancer cells on first contact. NK cells can destroy cancer cells before they multiply and cause disease.
Any abnormal cell that makes it through all of the body’s defenses becomes cancer. That cell will reproduce uncontrollably causing a mass of defective cells. These cells often do not provide the needed function and begin to crowd out those that do function normally. Because of the out of control cellular replication, even more mutations occur resulting in more aggressiveness, or malignancy, and increased resistance to cancer treatments.
The frenetic growth and reproduction of cells requires high metabolic activity and energy consumption. As the tumor grows, the abnormal cells secrete substances which cause the formation of new blood vessels (a process called angiogenesis) to feed its voracious appetite. The increased blood supply makes it easier for cancerous cells to slip into the blood stream and travel to other parts of the body to form new tumors, or metastasize.
Cancer is named for the cell type with which it originated, no matter where tumors may spread. So, breast cancer cells that metastasize to the bones are still called breast cancer.
When a tumor is biopsied a pathologist examines the cells microscopically to determine the type and character of the cancer. Based on the degree of abnormality seen, the tumor can be graded for the level of malignancy from 1 to 4. Grade 1 tumors are mildly aggressive while grade 4 cancers are highly malignant.
The grade of the tumor is not to be confused with the stage of cancer. Staging is also done on a scale of 1 to 4 but is a reflection of the size of the tumor, its location, and whether it has metastasized. Again, stage 4 cancer is the worst of the worst.
I have now introduced some basic cancer terminology and concepts, laying the groundwork for more helpful information to come. Cancer is a scary disease but there is much that can be done naturally to prevent or treat it. This is the first of a series of “Cancer Corner” posts that will help you understand and deal with this disease.
Have you had a pet with cancer?