How prevalent is cancer?
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Cancer is by no means a new disease as researchers have found evidence of cancer in dinosaur fossils and mummified remains of ancient civilizations. Yet because cancer is granted so much attention today it is easy to think of cancer as a modern biological phenomenon. However, it is more likely that cancer is merely a consequence of life, one that perhaps humans have significantly potentiated. Each year more than 550,000 Americans will die as a result of cancer–more than 1,500 Americans lives a day are cut short. In fact 23% of all deaths in the United States is caused by cancer making it the number 2 killer behind cardiovascular disease. Cancer Incidence Figure provides a breakdown of the relative amounts of cancer (e.g. breast, lung, colon, etc) in both men and women. |
Where does cancer come from?
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Like many diseases, cancer is merely an alteration of normal biological processes. It is not “caught” like the common cold but developed in the body. The basis of the cancer is the very foundation of life itself, cell reproduction. As a rule of nature, all cells must come from existing cells. In order to make a new cell, an existing cell grows in size, makes an exact copy of its DNA, and then divides into two identical cells, each with a complete copy of DNA. These two cells can then grow in size, copy their DNA, and divide, creating four cells total, and so on (see Cell Reproduction Figure). |
Throughout life, all tissue in the body grows in this manner until its genetically predetermined size is realized. Thus the brain and other organs will get only so big under normal conditions. At this point there are two possible scenarios. One scenario is that the current cells will exist for extremely long periods. For example, once tissue such as the brain, pancreas, and adrenals reach their intended size, their cells may exist for several decades or even throughout life. These cells simply are arrested in their ability to grow and divide.
The second scenario is that cells of a particular organ or tissue will continuously undergo turnover. The term turnover describes the balance between cells being broken down and those being made. New cells are constantly being made to replace cells of the same type that have a limited life span. The replaced cells are either broken down in the body, such as blood cells, or are removed from body surfaces, such as cells lining the digestive tract and skin cells. Cells that line the stomach and small intestine may have a life span of only a few days, while a red blood cell will live about four months.
How does cancer develop?
It is important to realize that almost all of the cells in the body inherently possess the ability to grow and divide and that these functions are tightly regulated by certain proteins within these cells. These cell proteins are ultimately produced from DNA genes. Quite simply, cancer is a disruption in this fine regulation. Cells that are arrested in their ability to reproduce can begin to reproduce. Or cells that are already reproducing at a specific rate, such as in the colon, uterus, or prostate, can reproduce at a rate greater than normal, thus resulting in more cells being produced than broken down.
What is the difference between a tumor and cancer?
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Not all forms of rapid uncontrolled cell growth are cancerous (see Tumor vs Cancer Table). Therefore, the term tumor is more appropriately applied to any unregulated cell growth. Once the presence of a tumor is recognized, the next step is to discern whether it is benign or malignant. The characteristics of benign compared to malignant are listed in the table below. It should be recognized that not all types of cancer are in the form of tumors. Leukemia is an example whereby the dangerous cells are blood cells, a fact that allows blood based cancers to easily spread through the body. |
Cancer is a disease that is in essence unregulated cell growth of a malignant nature. Thus, cancer is a malignant tumor. Because a benign tumor grows within a fibrous sack of connective tissue with uniform expansion boundaries, it can often be treated by surgical removal. However, malignant cell growth is not contained and does not show even and somewhat organized expansion. This certainly makes it more difficult to remove completely by surgery (see Tumor vs Cancer Table).
One deplorable characteristic of malignant cell growth is the ability of some of the cancerous cells to break away from the original tumor site. They then travel in the blood or through lymphatic circulation to find new residency and reproduce in a different region in the body. Thus the cancer is able to spread throughout the body (see Cancer Spread Figure).
What causes a normal cell to go awry?
One way a normal cell can be converted to a tumor-producing cell is by inflicted alterations in the associated genes in DNA. These genes are very special because they contain the instructions for a cell to make the proteins involved in the reproduction of that cell. The process of altering DNA is called a mutation and it takes several mutations in key proteins for a cell to transition into one that could give rise to a tumor. The factors that can cause mutations to genes include a variety of chemicals and ultraviolet (UV) light. Collectively, substances that can cause DNA mutations relevant to tumor production are referred to as carcinogenic agents. Carcinogenic means to potentially give rise to cancer.
Can we fix mutations before cancer develops?
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Fortunately, most mutations in DNA are not harmful. Researchers have estimated that the human body’s cells collectively face millions of these assaults on DNA every day. In many cases the mutation does not involve the cell reproduction genes and/or DNA-repair mechanisms quickly repair the damage. DNA repair involves “proofreading enzymes”, so called because they endeavor to check over the DNA, looking for abnormalities, and when found they fix them if they can. However, by exposing ourselves to more and more carcinogenic agents we increase the likelihood of developing tumors and cancer. |
How is cancer treated?
The treatment of cancer typically involves one of three medical options or a combination of them: surgical removal, radiation therapy, and chemotherapy. These are the proven or conventional modes of treatment. In addition, several other options (see Cancer Adjunctive Therapy Options Table) are available that can be used in conjunction with the conventional modes. These are often called complementary therapies.Surgical removal of cancerous tissue is somewhat tricky. If the tumor is benign, then cutting out the tumor is somewhat like removing seeds from an apple. However, when the tumor is cancerous, it may be spreading out within an area unpredictably, which makes it difficult to remove entirely. Theoretically speaking, if even one cancerous cell remains in the body, the tumor can regrow.
