(for example, breast cancer, lung cancer, colon cancer). Cancer is not confined to humans; animals and other living organisms can get cancer. Below is a schematic that shows normal cell division and how when a cell is damaged or altered without repair to its system, the cell usually dies. Also shown is what can occur when such damaged or unrepaired cells do not die and become cancer cells and proliferate with uncontrolled growth; a mass of cancer cells develop. Frequently, cancer cells can break away from this original mass of cells, travel through the blood and lymph systems, and lodge in other organs where they can again repeat the uncontrolled growth cycle. This process of cancer cells leaving an area and growing in another body area is termed metastatic spread or metastatic disease. For example, if breast cancer cells spread to a bone (or anywhere else), it means that the individual has metastatic breast cancer.
There are over 200 types of cancers; most can fit into the following categories according to the National Cancer Institute:
- Carcinoma: Cancer that begins in the skin or in tissues that line or cover internal organs
- Sarcoma: Cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue
- Leukemia: Cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of abnormal blood cells to be produced and enter the blood
- Lymphoma and myeloma: Cancers that begin in the cells of the immune system
- Central nervous system cancers: Cancers that begin in the tissues of the brain and spinal cord
In the U.S., according to the National Cancer Institute in 2010, the most common cancers (excluding non-melanoma skin cancers) are listed below.
| Cancer type | Estimated new cases | Estimated deaths |
| Bladder | 70,530 | 14,680 |
| Breast (female-male) | 207,090-1,970 | 39,840-390 |
| Colon and rectal (combined) | 142,570 | 51,370 |
| Endometrial | 43,470 | 7,950 |
| Kidney (renal cell) | 53,581 | 11,997 |
| Leukemia | 43,050 | 21,840 |
| Lung (including bronchus) | 222,520 | 157,300 |
| Melanoma | 68,130 | 8,700 |
| Non-Hodgkin lymphoma | 65,540 | 20,210 |
| Pancreatic | 43,140 | 36,800 |
| Prostate | 217,730 | 32,050 |
| Thyroid | 44,670 | 1,690 |
The three most common cancers in men, women and children in the U.S. are as follows:
- Men: Prostate, lung, and colorectal
- Women: Breast, colorectal, and lung
- Children: Leukemia, brain tumors, and lymphoma
The incidence of cancer and cancer types are influenced by many factors such as age, sex, race, local environmental factors, diet, and genetics. Consequently, the incidence of cancer and cancer types vary depending on these variable factors. For example, the World Health Organization (WHO) provides the following general information about cancer worldwide:
- Cancer is a leading cause of death worldwide. It accounted for 7.4 million deaths (around 13% of all deaths) in 2004 (statistics published in 2009).
- Lung, stomach, liver, colon, and breast cancer cause the most cancer deaths each year.
- Deaths from cancer worldwide are projected to continue rising, with an estimated 12 million deaths in 2030.
Different areas of the world may have cancers that are either more or less predominant then those found in the U.S. One example is that stomach cancer is often found in Japan, while it is rarely found in the U.S.
The objective of this article is to introduce the reader to general aspects of cancers. It is designed to be an overview of cancer and cannot cover every cancer type. This article will also attempt to help guide the reader to more detailed sources about specific cancer types.
What are the layers of the bladder?
The bladder consists of three layers of tissue. The innermost layer of the bladder which comes into contact with the urine stored inside the bladder is called the "mucosa" and consists of several layers of specialized cells called "transitional cells," which are almost exclusively found in the urinary system of the body. These same cells also form the inner lining of the ureters, kidneys, and a part of the urethra. These cells form a waterproof lining within these organs to prevent the urine from going into the deeper tissue layers.
The middle layer is a thin lining known as the "lamina propria" and forms the boundary between the inner "mucosa" and the outer muscular layer. This layer has a network of blood vessels and nerves and is an important landmark in terms of the staging of bladder cancer (described in detail below in the bladder cancer staging section).
The outer layer of the bladder comprises of the "detrusor" muscle and is called the "muscularis." This is the thickest layer of the bladder wall. Its main function is to relax slowly as the bladder fills up to provide low-pressure urine storage and then to contract to compress the bladder and expel the urine out during the act of passing urine. Outside these three layers is a variable amount of fat which lines and protects the bladder like a soft cushion and separates it from the surrounding organs such as the rectum and the muscles and bones of the pelvis.
What is bladder cancer?
Bladder cancer is an uncontrolled abnormal growth and multiplication of cells in the urinary bladder which have broken free from the normal control mechanisms of the body. Bladder cancer (like cancers of other organs) has the ability to spread (metastasize) to other body parts including the lungs, bones, and liver.
Bladder cancer invariably starts from the innermost layer of the bladder (for example, the mucosa) and may invade into the deeper layers as it grows. Alternately, it may remain confined to the mucosa for a prolonged period of time. Visually, it may appear in various forms. Most common is a shrub-like appearance (papillary) but it may also appear as a nodule, an irregular solid growth or a flat, barely perceptible thickening of the inner bladder wall (details in subsequent sections).
0 comments:
Post a Comment