Cancer is not just one disease, but a large group of almost one hundred diseases. Its two main characteristics are uncontrolled growth of the cells in thehuman body and the ability of these cells to migrate from the original siteand spread to distant sites. If the spread is not controlled, cancer can result in death.
Cancer, by definition, is a disease of the genes. A gene is a small part of DNA, which is the master molecule of the cell. Genes make "proteins," which allow our bodies to carry out all the many processes that permit us to breathe,think, move, etc. The genes also produce proteins that are involved in controlling the processes of cell growth and division. An alteration (mutation) tothe DNA molecule can disrupt the genes and produce faulty proteins. This causes the cell to become abnormal and lose its restraints on growth. The abnormal cell begins to divide uncontrollably and eventually forms a new growth known as a "tumor" or neoplasm (medical term for cancer meaning "new growth").
In a healthy individual, the immune system can recognize the neoplastic cellsand destroy them before they get a chance to divide. However, some mutant cells may escape immune detection and survive to become tumors or cancers. Tumors are of two types, benign or malignant. A benign tumor is slow growing, does not spread or invade surrounding tissue, and once it is removed, it doesn'tusually recur. A malignant tumor, on the other hand, invades surrounding tissue and spreads to other parts of the body. If the cancer cells have spread to the surrounding tissues, then, even after the malignant tumor is removed, it generally recurs.
A majority of cancers are caused by changes in the cell's DNA because of damage due to the environment. Environmental factors that are responsible for causing the initial mutation in the DNA are called carcinogens, and there are many types. There are some cancers that have a genetic basis. In other words, an individual could inherit faulty DNA from his parents, which could predispose him to getting cancer.
The major risk factors for cancer are: tobacco, alcohol, diet, sexual and reproductive behavior, infectious agents, family history, occupation, environment and pollution.
Despite the fact that there are several hundred different types of cancers, producing very different symptoms, the American Cancer Society (ACS) has established the following seven symptoms as possible warning signals of cancer:
- Changes in the size, color, or shape of a wart or a mole
- A sore that does not heal
- Persistent cough, hoarseness, or sore throat
- A lump or thickening in the breast or elsewhere
- Unusual bleeding or discharge
- Chronic indigestion or difficulty in swallowing
- Any change in bowel or bladder habits.
Diagnosis of cancer begins with a thorough physical examination and a complete medical history. The doctor will observe, feel and palpate (apply pressureby touch) different parts of the body in order to identify any variations from the normal size, feel and texture of the organ or tissue. As part of the physical exam, the doctor will inspect the oral cavity or the mouth. By focusing a light into the mouth, he will look for abnormalities in color, moisture,surface texture, or presence of any thickening or sore in the lips, tongue, gums, the hard palate on the roof of the mouth, and the throat. To detect thyroid cancer, the doctor will observe the front of the neck for swelling. He may gently manipulate the neck and palpate the front and side surfaces of the thyroid gland (located at the base of the neck) to detect any nodules or tenderness. As part of the physical examination, the doctor will also palpate thelymph nodes in the neck, under the arms and in the groin. Many illnesses andcancers cause a swelling of the lymph nodes.
The doctor may conduct a thorough examination of the skin to look for sores that have been present for more than three weeks and that bleed, ooze, or crust; irritated patches that may itch or hurt, and any change in the size of a wart or a mole.
Examination of the female pelvis is used to detect cancers of the ovaries, uterus, cervix, and vagina. In the visual examination, the doctor looks for abnormal discharges or the presence of sores. Then, using gloved hands the physician palpates the internal pelvic organs such as the uterus and ovaries to detect any abnormal masses. Breast examination includes visual observation where the doctor looks for any discharge, unevenness, discoloration, or scaling.The doctor palpates both breasts to feel for masses or lumps.
For males, inspection of the rectum and the prostate is also included in thephysical examination. The doctor inserts a gloved finger into the rectum androtates it slowly to feel for any growths, tumors, or other abnormalities. The doctor also conducts an examination of the testis, where the doctor observes the genital area and looks for swelling or other abnormalities. The testicles are palpated to identify any lumps, thickening or differences in the size,weight and firmness.
If the doctor detects an abnormality on physical examination, or the patienthas some symptom that could be indicative of cancer, the doctor may order diagnostic tests. Laboratory studies of sputum (sputum cytology), blood, urine,and stool can detect abnormalities that may indicate cancer. Imaging tests such as computed tomography scans (CT scans), magnetic resonance imaging (MRI),ultrasound and fiberoptic scope examinations help the doctors determine thelocation of the tumor even if it is deep within the body. Conventional x raysare often used for initial evaluation, because they are relatively cheap, painless and easily accessible.
The most definitive diagnostic test is the biopsy, wherein a piece of tissueis surgically removed for microscope examination. Besides, confirming a cancer, the biopsy also provides information about the type of cancer, the stage it has reached, the aggressiveness of the cancer and the extent of its spread.Since a biopsy provides the most accurate analysis, it is considered the gold standard of diagnostic tests.
The aim of cancer treatment is to remove all or as much of the tumor as possible and to prevent the recurrence or spread of the primary tumor. While devising a treatment plan for cancer, the likelihood of curing the cancer has to be weighed against the side effects of the treatment. If the cancer is very aggressive and a cure is not possible, then the treatment should be aimed at relieving the symptoms and controlling the cancer for as long as possible.
Cancer treatment can take many different forms, and it is always tailored tothe individual patient. The decision on which type of treatment is the most appropriate depends on the type and location of cancer, the extent to which ithas already spread, the patient's age, sex, general health status and personal treatment preferences. The major types of treatment are: surgery, radiation, chemotherapy, immunotherapy, hormone therapy, and bone-marrow transplantation.
Surgery is the removal of a visible tumor and is the most frequently used cancer treatment. It is most effective when a cancer is small and confined to one area of the body.
Radiation kills tumor cells. Radiation is used alone in cases where a tumor is unsuitable for surgery. More often, it is used in conjunction with surgeryand chemotherapy. Radiation can be either external or internal. In the external form, the radiation is aimed at the tumor from outside the body. In internal radiation (also known as brachytherapy), a radioactive substance, in the form of pellets or liquid is placed at the cancerous site by means of a pill,injection or insertion in a sealed container.
Chemotherapy is the use of drugs to kill cancer cells. It destroys the hard-to-detect cancer cells that have spread and are circulating in the body. Chemotherapeutic drugs can be taken either orally (by mouth) or intravenously, andmay be given alone or in conjunction with surgery, radiation or both.
Immunotherapy uses the body's own immune system to destroy cancer cells.Thisform of treatment is being intensively studied in clinical trials and is notyet widely available to most cancer patients. The various immunological agents being tested include substances produced by the body (such as the interferons, interleukins, and growth factors), monoclonal antibodies and vaccines. Unlike traditional vaccines, cancer vaccines do not prevent cancer. Instead, they are designed to treat people who already have the disease. Cancer vaccineswork by boosting the body's immune system and training the immune cells to specifically destroy cancer cells.
Hormone therapy is standard treatment for some types of cancers that are hormone-dependent and grow faster in the presence of particular hormones. These include cancer of the prostate, breast, and uterus. Hormone therapy involves blocking the production or action of these hormones. As a result the growth ofthe tumor slows down and survival may be extended for several months or years.
The bone marrow is the tissue within the bone cavities that contains blood-forming cells. Healthy bone marrow tissue constantly replenishes the blood supply and is essential to life. Sometimes, the amount of drugs or radiation needed to destroy cancer cells also destroys bone marrow. Replacing the bone marrow with healthy cells counteracts this adverse effect. A bone marrow transplant is the removal of marrow from one person and the transplant of the blood-forming cells either to the same person or to some one else. Bone-marrow transplantation, while not a therapy in itself, is often used to "rescue" a patient, by allowing those with cancer to undergo very aggressive therapy.
Many different specialists generally work together as a team to treat cancerpatients. An oncologist is a physician who specializes in cancer care. The oncologist provides chemotherapy, hormone therapy, and any other non-surgical treatment that does not involve radiation. The oncologist often serves as theprimary physician and co-ordinates the patient's treatment plan. The radiation oncologist specializes in using radiation to treat cancer, while the surgical oncologist performs the operations needed to diagnose or treat cancer.
There are a multitude of alternative treatments available to help the personwith cancer. They can be used in conjunction with, or separate from, surgery,chemotherapy, and radiation therapy. Alternative treatment of cancer is a complicated arena and a trained health practitioner should be consulted.
Most cancers are curable if detected and treated at their early stages. A cancer patient's prognosis is affected by many factors, particularly the type ofcancer the patient has, the stage of the cancer, the extent to which it hasmetastasized and the aggressiveness of the cancer. In addition, the patient'sage, general health status and the effectiveness of the treatment being pursued are also important factors.
According to nutritionists and epidemiologists from leading universities in the United States, a person can reduce the chances of getting cancer by following some simple guidelines:
- Eating plenty of vegetables and fruits
- Exercising vigorously for at least 20 minutes every day
- Avoiding excessive weight gain
- Avoiding tobacco (even second hand smoke)
- Decreasing or avoiding consumption of animal fats and red meats
- Avoiding excessive amounts of alcohol
- Avoiding the midday sun (between 11 a.m. and 3 p.m.) when the suns rays are the strongest
- Avoiding risky sexual practices
- Avoiding known carcinogens in the environment or work place.