What is Cancer?
Cancer is the abnormal growth, reproduction and spread of body cells. The human body contains trillions of cells grouped to make tissues such as muscles, bones and skin.
Most normal cells grow, reproduce and die in response to signals inside and outside the body. If these processes occur in a balanced and orderly way, the body remains healthy and functions normally. Problems can begin when normal cells mutate, or change, into cancer cells.
A normal cell can become a cancer cell for no apparent reason or because of repeated or heavy exposure to a carcinogenic, or cancer-causing, substance such as tobacco or alcohol.
Both the behavior and appearance of cancer cells differ from normal cells. Mutation occurs in the cell's DNA, or genetic material. DNA controls the cell's behavior and appearance.
Once DNA has mutated, the cell is different from the healthy cells nearby. The mutated cell appears different and functions in other ways from normal cells. The mutated cell detaches from its neighbors and does not "know" when to stop growing or die.
In a sense, the mutated cell does not "obey" the internal signals that control the other cells and behaves independently rather than cooperatively.
The mutated cell divides into two new mutated cells that divide into four mutated cells. This process continues until the mutated cells form a mass called a tumor.
A tumor can be self-contained, a condition where the mutated cells will not invade surrounding tissue or travel through the bloodstream to other sites. A self-contained tumor, such as a wart, is benign and is generally not life-threatening and usually can be surgically removed.
If tumor cells grow and divide, damage surrounding normal cells, and invade other body sites, the tumor is malignant, or cancerous. The greatest danger in a malignant tumor is its ability to spread throughout the body in a process called metastasis.
During a metastasis, the tumor cells grow, divide and eventually enter the bloodstream. There, the tumor cells travel to other body sites, implanting themselves in healthy tissue and growing into new malignant tumors.
As tumors grow and multiply they rob normal healthy cells of their nutrients and oxygen. Gradually, with the progression of the cancer, healthy cells die and the patient's health and functions deteriorate, often resulting in death.
More than 100 different diseases are classified as a type of cancer. These diseases include leukemia, non-Hodgkins disease, myeloma and melanoma.
Most cancers fall into one of three main groups: carcinomas, sarcomas, or leukemia and lymphoma.
Carcinomas include cancers that originate from cells that form the skin (such as skin cancer), line the internal organs (such as lung cancer), or form glands (such as breast cancer). Sarcomas include cancers that originate from connective tissues such as bone and cartilage (such as osteosarcoma, or bone cancer) or from muscle tissues (such as rhabdomyosarcoma, or a malignant tumor in skeletal muscle).
Leukemia and lymphoma include cancers that originate from blood-forming cells and cells within the immune system, respectively. This group includes Hodgkin's lymphoma, which is a cancer of the lymph nodes, and granulocytic leukemia, which is a cancer of the white blood cells.
In the United States, skin cancer is the most frequent type of cancer. Breast cancer is the next most frequent type, followed by lung cancer, prostate cancer, colon and rectal cancer, bladder cancer, uterine cancer, oral cancer, leukemia and pancreatic cancer.
Formerly, a cancer diagnosis meant certain death. Today, modern medical treatment enables most cancer patients to live longer, healthier lives. Many other cancer patients will recover completely.
What Causes Cancer?
Understanding the various causes of cancer has been an ongoing challenge. For instance, getting an X-ray was once considered completely safe. Today scientists know that prolonged exposure to the type of radiation in X-rays can lead to cancer.
Cancer develops from changes in the DNA, or genetic material, of the body's cells, causing them to grow and reproduce uncontrollably. Scientists believe four factors can promote these cellular changes: environment, diet, heredity and lifestyle.
Ultraviolet light or solar radiation is the leading cause of skin cancer. The most common skin cancers are non-melanomas, which spread slowly and, if detected in time, are likely curable. Excessive sun exposure is also associated with melanoma, a serious form of skin cancer, which can spread rapidly to other body sites.
Of all skin color types, fair-skin people are most sensitive to skin cancers, but dark-skin people, too, should take these precautions:
- limit amount of sun exposure, especially between 10 a.m. and 3 p.m.
- wear sunscreen
- wear protective clothing
Radiation such as the kind in X-rays, nuclear power plants, and nuclear weapons also can cause cancer. The risk of getting cancer depends on how much exposure an individual gets. The average radiation dose in a single X-ray is low, so the risk is small. However, because effects of radiation can accumulate over time, people should avoid unnecessary exposures.
We have launched some cancer-causing chemicals into the environment through air pollution. These cancer-causing chemicals include benzene and vinyl chloride, which some factories discharge into streams, rivers and other bodies of water. Though the amounts are small in human terms, they become concentrated in fish and can cause cancer in them. When people are in areas of high industrial pollution, water purification is advised. Do not eat fish caught in polluted waters, since the fish might also contain large amounts of the chemicals.
Some people are exposed to carcinogens at work. The first link between occupation and cancer was noted in 18th-century England where physicians saw high rates of cancer in men who were chimney sweeps in their youth. The physicians determined exposure to soot in the chimneys had caused the cancer. Once the sweeps wore protective clothing and routinely cleaned the soot off their bodies, the cancer rate dropped.
Asbestos is another occupational carcinogen. The association between lung cancer and asbestos became clear in the 1950s; 10 years later, regulations limiting asbestos in the workplace were enacted. Occupational exposure might be related to up to 5 percent of cancer deaths.
Foods such as hot dogs, bacon, ham and pickled meats and fish have preservatives called nitrites. Nitrites convert to another chemical called nitrosamines, which are known cancer-causing agents. Researchers have linked an increased risk of stomach cancer to overconsumption of smoked or cured foods. Eating such foods only occasionally is not harmful.
Researchers have linked a diet high in calories and fat to an increase in cancer. People in the United States consume more fat than in other countries, resulting in a higher incidence of breast cancer and colon cancer. Consuming large amounts of refined sugars with a high-fat diet increases the risk of developing colon cancer. Cutting back on fatty foods or using low-fat substitutes lowers the risk of contracting these kinds of cancer.
Fruits, vegetables and whole grain breads and cereals are low in fats, high in nutrients, and contain ingredients that may reduce cancer risk. Carrots are high in beta-carotene, which metabolizes to form vitamin A. Diets rich in beta-carotene have reduced the occurrence of some cancers, including lung, esophagus, stomach, bladder and breast. Vitamins C and E, found in lettuce and salad greens, help reduce cancer risks by decreasing the formation of the carcinogenic nitrosamines.
Fruits, vegetables and grains might protect against colon and rectal cancer because they contain much dietary fiber. Fiber is indigestible plant material that helps clean out the large intestine, preventing accumulation of fecal material that might promote cancerous cell growth.
Although people cannot inherit most cancers, they can pass down a susceptibility to developing cancer. Careful cancer screening, cancer tests and preventive measures are advised if the family history includes cancer.
Cigarette smoking is the major cause of cancer in the United States and leads to almost one-third of cancer deaths in the United States. Researchers directly link smoking to cancer of the lung, mouth, throat, bladder, kidney and pancreas. Tobacco contains many carcinogens that promote cell mutation and growth. Even breathing secondhand smoke may be associated with an increase in lung cancer.
Too much alcohol can lead to cirrhosis, a liver disease resulting from chronic liver tissue damage. Cirrhosis can lead to liver cancer. Researchers also relate excess alcohol consumption to mouth and throat cancers. Excessive drinking combined with smoking increases this incidence.
People who exercise have lower death rates from cancer than do people who do not exercise. Exercise reduces a person's fat ratio and improves immune system function. Some studies show that exercise may prevent malignant cells from spreading.
Treatments for Cancer
Treatment for cancer has progressed rapidly over the last 30 years. Doctors generally prescribe three main treatments for cancer: surgery, radiation therapy, chemotherapy or a combination of these. Choosing a course of medical treatment depends largely on the cancer type, stage of progression, and location.
Surgery is generally advisable when physicians can safely remove the cancer from the body. Today, physicians take great care to leave healthy tissue intact and remove only the cancerous portion. For instance, in a breast lumpectomy, surgeons remove the breast tumor and a small area of tissue surrounding it, while leaving most of the breast intact.
In situations where the cancerous cells have spread, surgeons sometimes must remove large areas of healthy tissue along with the tumor to insure that no malignancy remains. In these cases, physicians remove lymph nodes from the tumor area because cancer can spread through nodes. If removing all the lymph nodes does not eliminate the malignancy, physicians combine some surgical procedures with either chemotherapy or radiation therapy to kill any malignancy that may remain after surgery.
Physicians use radiation therapy to destroy cancer cells. Ironically, radiation can cause and destroy cancer. Health workers administer radiation in several different ways. Sometimes, they inject it into the bloodstream, where it circulates throughout the body, finding the cancer and destroying it. In other cases, they implant radioactive capsules directly into the tumor.
The most common form of radiation therapy is machine radiation, which focuses a small beam of radiation directly at the tumor. Radiation kills all the cancer cells in the beam's focus. The radiation beam goes through the body and the tumor, without killing all the cells along its path. To kill only the tumor, health workers control the machine so the radiation beam rotates. As the beam rotates, it remains focused on the tumorous area long enough to be lethal. The surrounding healthy cells receive some radiation, but not enough to kill them. Side effects of radiation therapy include radiation sickness, which are nausea and skin redness in the tumor area.
Chemotherapy uses poison drugs that take advantage of cancer cells' rapid growth and consumption of large amounts of nutrients. Chemotherapy side effects include nausea and temporary full or partial hair loss. Antimetabolites, one group of these drugs, work by mimicking the nutrients the body's cells consume. Physicians inject these drugs into the bloodstream, where they travel throughout the body, consumed by every cell. Rapidly growing cancerous cells consume much more of the poisonous drugs than do normal cells. As a result, the drugs destroy cancerous cells faster than normal cells.
Cells reproduce by duplicating their genetic code, or DNA. Another group of chemotherapy drugs interferes with the duplication of DNA, so cells cannot reproduce. Chemotherapy drugs act on all the patient's cells -- the cancerous cells and the healthy cells. A physician's challenge is to administer the drugs to kill only the cancer cells, not the healthy cells. A new group of drugs, called monoclonal antibodies, is designed to affect only cancer cells, leaving healthy cells intact.
Researchers have refined these three cancer treatments (surgery, radiation therapy and chemotherapy) over the past 20 years. As a result, the survival rate among cancer patients has increased dramatically. But, the success of any treatment for cancer depends on how much the cancer has spread before treatment begins. Once cancer metastasizes, or spreads into different areas of the body, treating it with surgery, radiation therapy or chemotherapy becomes more difficult. As the tumor mass increases and cancerous cells proliferate, the cancer may become resistant to any type of therapy medicine can provide.
Early cancer detection is critical to successful treatment. If physicians destroy tumors before they have had an opportunity to spread, a person with cancer has a much greater chance for survival.
All About Prostate Cancer
Prostate cancer is a malignancy that develops in the prostate gland, a gland that is important for the proper function of the male reproductive tract. Cancer of the prostate is the most common cancer among American men, affecting about one in five men during the course of a lifetime.
Although incidence increases with age, this cancer can occur in younger men as well. This form of cancer very often occurs even without symptoms.
Understanding Your Body
The prostate is a walnut-shaped gland located just below the bladder and just in front of the rectum. The prostate secretes fluids and enzymes that make up about one-third of the spermatic fluid leaving the body during ejaculation.
The sperm in the ejaculate is made in the testicles and transported through a tube called the vas deferens. This tube also passes through and receives contributions from the prostate before reaching the urethra. The urethra is the tube inside the penis through which urine and ejaculate pass.
The seminal vesicles are glands that lie right behind and slightly above the prostate. These glands also secrete fluids, which are added to the ejaculate.
Because of the proximity and direct physical connection to the prostate, cancer can sometimes spread to the seminal vesicles or the prostate capsule (fibrous capsule that surrounds the prostate). If this occurs, surgery is usually unable to remove the entirety of the cancer.
Because the prostate is situated immediately in front of the rectum, the doctor can feel the contour of the prostate when he or she performs a rectal examination. A normal prostate gland is smooth and firm, but not hard.
Who Gets Prostate Cancer?
The cause of prostate cancer is not yet known. However, doctors do know that certain factors increase the risk of getting the cancer.
One factor is a family history of prostate cancer. If the patient has a father or brother with the disease, his chances of developing prostate cancer are two times greater.
Older men are also at greater risk. Three-quarters of all reported cases occur in men age 65 and older. Race is another factor that affects one's risk.
African-American men have the highest incidence of prostate cancer in the world, are two times more likely to be diagnosed with the disease, and two-and-a-half to three times more likely to die of prostate cancer.
There is evidence that suggests that prostate cancer may be related to male hormone levels. Eunuchs (men that have been castrated) do not get the disease, suggesting that the male hormones produced by the testicles influence the development of prostate cancer.
Men with severe liver disease leading to increased blood levels of estrogen (the female sex hormone) have a decreased risk in prostate cancer.
Prostate cancer also may be related to environmental factors. As mentioned above, African Americans have one of the highest rates of prostate cancer in the world. Black Africans, however, have a low incidence of prostate cancer when compared to the high rates in African Americans.
The Asian population has a low risk of prostate cancer. For instance, Japanese men have an incidence of prostate cancer that is 40 times lower than in Afican American men.
It is interesting to note that when Asians immigrate to the United States, their incidence of prostate cancer rises. It is possible that differences in the environment, or the types of food people eat, may help to explain these observations, but that remains to be proven.
All About Skin Cancer
One-half of all new cancers are skin cancers, making skin cancer the most common cancer. Skin cancers can occur on any portion of the body, although they are most commonly found on areas that are exposed to sunlight.
There are three main types of skin cancers. Basal cell carcinomas (80 percent of all skin cancers), are the easily treated type and usually appear as slow-growing raised areas that may crust and bleed, occurring mostly on the face, neck and hands. Squamous cell carcinomas (16 percent of skin cancers), are red or pink scaly bumps, typically appearing on the face, hands and ears.
Malignant melanomas (4 percent of skin cancers), can be successfully treated if caught early. This is the most serious type, usually beginning as a light brown or black, flat spot with irregular borders that later can become red, blue or white. It often grows from a mole. This latter type of skin cancer, malignant melanoma, is rare in patients of African American descent. All three types of skin cancer are caused mainly by too much exposure to the sun.
Understanding Your Body
Let us take a closer look at the structure of skin and where cancer develops. The skin includes three layers, these are the epidermis, dermis and subcutaneous tissue. The subcutaneous tissue, or inner most layer, is predominantly fat. The middle layer, the dermis, contains hair follicles, sweat glands and supportive tissue that includes collagen and elastic tissue.
When the sun's rays penetrate the dermis, they eventually break up the elastic tissue and collagen, this forms the basis of the development of wrinkles. The top layer is called the epidermis. It is this layer that regenerates itself on a regular basis and protects the skin against ultraviolet light.
This protection is in the form of melanin (pigment) which is produced in specialized cells within the epidermis called melanocytes. The other types of cells seen within the epidermis are basal cells (reproducing cells) and squamous cells. When basal cells divide, they push the older cells upward, causing them to flatten. These flattened cells are the squamous cells.
The melanocytes, located in and among the basal cells, produce melanin. Melanocytes are cells that have processes called dendrites that allow them to put the melanin into the basal cells which provides the nucleus with protection from ultraviolet light.
Melanin is one factor that gives skin its color. When skin is exposed to ultraviolet (UV) light, more melanin than normal is released from melanocytes in order to protect the skin from damage. This darkening appears as a tan although it signifies damaged skin.
If squamous cells are damaged by ultraviolet light, they may divide abnormally and form a mass. This mass is a squamous cell carcinoma, a cancer. If the mass forms in the basal layer, it is called a basal cell carcinoma. When melanocytes grow out of control, the result may be the most serious form of cancer, malignant melanoma.
Who Gets Skin Cancer?
Everyone gets exposed to the sun. So why do some people get skin cancers while others do not? The most significant common factor among skin cancer patients is fair skin. Lighter skin usually does not have enough melanin to protect it.
Skin cancer does develop in a small number of African Americans, but usually appears on lighter parts of their bodies. The tendency to get skin cancer runs in families, partly because skin types tend to be inherited. It also is believed that certain genes might contribute to skin cancer.
Looking inside the nucleus of a typical cell of the body we see long twisted bands of a material called DNA. It contains all of the instructions for the body's makeup, such as height, eye color and hair color. The DNA also tell cells how and when to divide.
When the DNA becomes damaged by ultraviolet light of the sun, in the case of skin cells, the DNA can no longer tell cells how to divide in a regular fashion. The cells now divide at an abnormal rate without proper DNA instructions. Without this regulatory function, cells divide uncontrollably and form masses of extra tissue. These masses become skin cancer.
Fortunately, the majority of skin cancers are local growths and do not spread from the site of origin. Malignant melanoma is one that can and does spread from its site of origin. The spread of cancer cells from their original location to other parts of the body is called metastasis.
Skin Cancer Symptoms and Findings
Skin cancers have very minimal, if any symptoms. Itching of a pigmented spot may be a symptom of the development of malignant melanoma. Basal cell cancers and squamous cell cancers are usually asymptomatic but alert you to their presence by growth, crusting or roughness.
Basal cell and squamous cell carcinomas commonly occur in sun exposed areas, most commonly on the face. Basal cell carcinomas are raised areas with a smooth surface over which delicate blood vessels may crust and bleed. Oftentimes the border is more raised than the center. As the basal cell carcinoma continues to grow, the center may form an ulcer.
Squamous cell carcinomas usually have a rough scaly surface and, like basal cell carcinomas, are more common on sun-exposed areas although they may occur on nonexposed areas.
Malignant melanomas are distinctive in that they are most commonly brown or black in color, with an irregular border, and often times have multiple colors within the lesion, these being brown, red-brown, and violet. They occur with greater frequency on the legs of women and the backs of men.
One should use the American Cancer Society's recommendation for determining whether or not you think a spot or mole should be checked by your doctor. This is called the A-B-C-D method of spots and/or moles.
The A stands for asymmetry; if you divide a mole or spot in half, one side will be different than the other side. B stands for border; the border should be regular and not have jagged edges. C stands for color; the color has some variety. D stands for diameter; it is usually bigger than a quarter-inch or the end of a pencil eraser.
If there is any doubt or suspicion on your part, it is best to have these spots/moles checked by your dermatologist or family physician.
Skin Cancer Wellness and Prevention
Most skin cancers appear on the parts of the body that are exposed to the sun. Sun protection is an essential part of the prevention of skin cancers. Some skin cancers do not appear in sun exposed areas and it is thought that they are genetically related.
By protecting ourselves from the sun, and more importantly by protecting children from future sun exposure, we can try to avoid developing skin cancer in later life. A good way to protect yourself from the sun is to use a sunscreen preparation that can absorb ultraviolet (UV) rays before they penetrate the skin.
Choose a preparation that protects you from both UVA and UVB rays. Also look for what is called the SPF (sun protection factor) number on the bottle. The higher the number, the better the protection. Most experts agree that people should wear lotion with at least a SPF of 30.
Sun protection products should be applied 20 to 30 minutes before going outdoors so they have an opportunity to bind to the surface of the skin, so that they are fully effective once the individual is outside. Sweating and immersion in water will require the reapplication of these materials. The use of a hat and sun protective garments are also important in protecting one from the affects of ultraviolet light.
The use of sun protective lotions and clothing does not give one license to bask in the sunlight with impunity. Avoidance of sun between the hours of 10 a.m. and 3 p.m. is an effective measure in preventing sun damage to your skin.