Cancer

Any of a group of diseases that are characterized by the abnormal and unrestrained growth of cells in body organs or tissues. Cancerous tumours can form in any tissue in the body, but they most commonly develop in major organs, such as in the lungs, breasts, intestines, skin, stomach, or pancreas. Cancerous tumours can also develop in the nasal sinuses, the testes or ovaries, or the lips or tongue. Cancers may also develop in the tissues of the bone marrow that form blood cells (see leukaemia) and in the lymphatic system, the muscles, or the bones.

Cancers differ from benign (non- cancerous) neoplasms (growths) in that they spread and infiltrate surrounding normal tissue. The tumours can cause blockages in hollow organs, such as within the digestive tract. They can also destroy nerves and erode bone. Cancer cells may also spread through the blood vessels or lymphatic system to other organs to form secondary tumours, known as metastases.

Causes

Tumour-forming cells develop when the oncogenes (genes controlling cell growth and multiplication) in a cell or cells undergo a series of changes. A small group of abnormal cells develop that divide more rapidly than normal, lack differentiation (they no longer perform their specialized task), and may escape the normal control of hormones and nerves. Possible causes of cancer include environmental factors (such as sunlight and pollutants), alcohol consumption, dietary factors, and, most particularly, smoking, which is responsible for more cancers than any other agent. All of these factors may provoke critical changes within body cells in people who are already susceptible to developing cancer. Susceptibility to certain cancers may be inherited.

Symptoms

Cancer symptoms depend on the site of the growth, the tissue of origin, and the extent of the tumour. They may be a direct feature of the growth (for example, lumps or skin changes) or may result from disruption of the function of a vital organ or blockage of a part of the body by the tumour. Unexplained weight loss is a feature of many different types of cancer.

Diagnosis

Screening tests are increasingly being used to detect early signs of certain types of cancer in people who are thought to be at risk. Early detection of cancer optimizes the chance of a cure; for this reason, screening for breast cancer, cancer of the cervix, and intestinal cancer has reduced mortality from these tumours. Diagnosis of cancer after symptoms have appeared is based on a physical examination, and confirmed by biopsy (removal of a sample of abnormal tissue for microscopic analysis) and imaging tests. There are four main types of procedure used to detect cancer: cytology (cell) tests, imaging techniques, chemical tests, and direct inspection.

Treatment and outlook

Many cancers are now curable, usually by combinations of surgery, radiotherapy, and anticancer drugs.

Detailed articles about cancer:

Types of cancer

Cancer in more detail - non-technical

Definition

Cancer is not just one disease, but a large group of over 100 diseases. Its two main characteristics are uncontrolled growth of the cells in the human body and the ability of these cells to migrate from the original site and spread to distant sites. If the spread is not controlled, cancer can result in death.

Demographics

About 1.5 million Americans are diagnosed with cancer annually. One out of every four deaths in the United States is from cancer. More than 562,000 people in the United States are anticipated to die of cancer in 2009. This equates to more than 1,500 deaths from cancer per day. Overall, cancer death rates for both men and women have decreased since 2004. However, cancer ranks as the number one cause of death in persons under the age of 85 and ranks second only to heart disease as a cause of death overall in the United States.

Since the occurrence of cancer increases as individuals age, most of the cases are seen in adults, middle-aged or older. Seventy-seven percent of all cancers are diagnosed in people who are older than 55 years of age. The probability of an American male developing an invasive cancer or dying from cancer in his lifetime is 1 in 2; for American females the probability is 1 in 3.

The most common cancers are skin cancer, lung cancer, colon cancer, breast cancer (in women), and prostate cancer (in men). In addition, cancer of the kidneys, ovaries, uterus, pancreas, bladder, rectum, and blood and lymph node cancer (leukaemias and lymphomas) are also included among the 12 major cancers that affect most Americans.

Although most cancer occurs in adults, in the United States cancer is still responsible for more deaths in children under age 20 than any other disease. Each year, about 12,500 new cases of cancer are diagnosed in children compared to 1.5 million new cases annually in adults. About 2,300 children die of cancer in the U.S. each year. In general, children respond better to cancer treatment than adults do. Advances in treatment have resulted in better outcomes and increased long-term survival rates for children. Eighty percent of children newly diagnosed with cancer now live at least 5 years compared to about 60% in the mid- 1970s. However, the incidence of cancer in children, especially acute lymphocytic leukemia and brain cancer, has increased steadily for the past 30 years.

Description

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 are the ultimate workhorses of the cells. These proteins allow the body to carry out all the many processes that permit an individual to function—to breathe, think, and move.

Throughout people’s lives, the cells in their bodies are growing, dividing, and replacing themselves. Many genes produce proteins that are involved in controlling the processes of cell growth and division. An alteration (mutation) to the 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 even tually 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 cells and 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 not considered cancer. It is typically slow-growing, does not spread or invade surrounding tissue, and once it is removed, does not usually recur. A malignant tumor, by contrast, is cancer. It invades surrounding tissue and spreads to other parts of the body. If the cancer cells have spread to the surrounding tissues, 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 to the environment. Environmental factors that are responsible for causing the initial mutation in the DNA are called carcinogens, of which there are many types.Some cancers have a genetic or inherited basis. In other words, individuals can inherit faulty DNA from a parent, which could predispose the person to getting cancer. While there is scientific evidence that both factors (environmental and genetic) play a role, less than 10% of all cancers are strictly linked to hereditary factors. Cancers that are known to have a hereditary link are breast cancer, colon cancer, ovarian cancer, and uterine cancer. Besides genes, certain physiological traits could be inherited and could contribute to cancers. For example, inheriting fair skin makes a person more likely to develop skin cancer, but only if that person also has prolonged exposure to intensive sunlight.

There are several different types of cancers:

  • Carcinomas are cancers that arise in the epithelium (the layer of cells covering the body’s surface and lining the internal organs and various glands). Ninety percent of human cancers fall into this category. Carcinomas can be subdivided into two types: adenocarcinomas (those that develop in an organ or a gland) and squamous cell carcinomas (squamous-cell carcinoma (SCC or SqCC) is a cancer of a kind of epithelial cell, the squamous cell. These cells are the main part of the epidermis of the skin, and this cancer is one of the major forms of skin cancer. However, squamous cells also occur in the lining of the digestive tract, lungs, and other areas of the body, and SCC occurs as a form of cancer in diverse tissues, including the lips, mouth, esophagus, urinary bladder, prostate, lung, vagina, and cervix, among others.)
  • Melanomas also originate in the skin, usually in the pigment cells (melanocytes).
  • Sarcomas are cancers of the supporting tissues of the body, such as bone, muscle, and blood vessels.
  • Cancers of the blood and lymph glands are called leukemias and lymphomas, respectively.
  • Gliomas are cancers of the nerve tissue.

Risk factors

The major risk factors for cancer are related to: tobacco and alcohol use, dietary factors, sexual and reproductive behavior, exposure to infectious agents, family history, occupation, and environmental factors including pollution.

Causes and symptoms

According to estimates of the American Cancer Society (ACS), approximately 40% of cancer deaths in 2009 were anticipated to be due to tobacco and excessive alcohol use. An additional one-third of the deaths were expected to be related to being overweight, being obese, lacking physical activity, and having poor nutrition.

Many of the one million skin cancers diagnosed in 2009 were believed to be a direct result of over-exposure to ultraviolet light from the sun’s rays.

Tobacco

Eighty to 90% of lung cancer cases occur in smokers. Smoking has also been shown to be a contributory factor in cancers of the upper respiratory tract, esophagus, larynx, bladder, pancreas, and probably liver, stomach, breast, and kidney as well. In the 2000s, scientists also confirmed that secondhand smoke (or passive smoking) can increase one’s risk of developing cancer.

Alcohol

Excessive consumption of alcohol is a risk factor in certain cancers, such as liver cancer. Alcohol, in combination with tobacco, significantly increases the chances that an individual will develop mouth, pharynx, larynx, and esophageal cancers.

Diet

Thirty-five percent of all cancers are due to dietary causes. Excessive intake of fat leading to obesity has been associated with cancers of the breast, colon, rectum, pancreas, prostate, gall bladder, ovaries, and uterus.

Sexual and reproductive behavior

The human papillomavirus (HPV), which is sexually transmitted, has been shown to cause cancer of the cervix. Having multiple sexual partners and becoming sexually active at an early age have been shown to increase one’s chances of contracting HPV. In addition, it has also been shown that women who do not have children or have children later in life have an increased risk for both ovarian and breast cancer.

Infectious agents

Between 1985 and 2005, scientists obtained evidence to show that approximately 15% of the world’s cancer deaths can be traced to viruses, bacteria, or parasites.

Family history

Certain cancers such as breast, colon, ovarian, and uterine cancer recur generation after generation in some families. A few cancers, such as the eye cancer retinoblastoma, a type of colon cancer, and a type of breast cancer known as early-onset breast cancer, have been shown to be linked to certain genes that can be tracked within a family. It is, therefore, possible that inheriting particular genes makes a person susceptible to certain cancers.

Occupational hazards

There is evidence to show that certain occupational hazards account for 4% of all cancer deaths. For example, asbestos workers have an increased incidence of lung cancer. Similarly, a higher likelihood of getting bladder cancer is associated with dye, rubber, and gas workers; skin and lung cancer with smelters, gold miners, and arsenic workers; leukemia with glue and varnish workers; liver cancer with PVC manufacturers; and lung, bone, and bone marrow cancer with radiologists and uranium miners.

Environment

Radiation is believed to cause 1 to 2% of all cancer deaths. Ultra-violet radiation from the sun accounts for a majority of melanoma deaths. Other sources of radi- ation are x rays, radon gas, and ionizing radiation from nuclear material. Pollution Several studies have shown a link between asbestos and cancer. Chlorination of water may account for a small rise in cancer risk. However, the main danger from pollution occurs when dangerous chemicals from industries escape into the surrounding environment. It has been estimated that 1% of cancer deaths are due to air, land, and water pollution.

Symptoms

Cancer is a progressive disease and goes through several stages. Each stage may produce a number of symptoms. Some symptoms are produced early and may occur due to a tumor that is growing within an organ or a gland. As the tumor grows, it may press on the nearby nerves, organs, and blood vessels. This causes pain and some pressure, which may be the earliest warning signs of cancer.

Despite the fact that there are over 100 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

Many other diseases besides cancer can produce the same symptoms. However, it is important to have these symptoms checked, as soon as possible, especially if they linger. The earlier a cancer is diagnosed and treated, the better the chance of cure. Many cancers such as breast cancer may not have any early symptoms. Therefore, it is important to undergo routine screening tests such as breast self-exams and mammograms.

Diagnosis

Examination

Diagnosis of many cancers begins with a thorough physical examination and a complete medical history.

The doctor will observe, feel, and palpate (apply pressure by 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 patient’s mouth. By focusing a light into the mouth, the physician 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 the lymph nodes in the neck, under the arms, and in the groin. Many illnesses and cancers 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 mass. 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 testicles, rectum and the prostate is also included in the physical examination. The doctor inserts a gloved finger into the rectum and rotates it slowly to feel for any growths, tumors, or other abnormalities. The doctor also conducts an examination of the testes, in which 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.

Tests

The doctor may order diagnostic tests if an abnormality has been detected on physical examination, or if the patient has some symptom that could be indicative of cancer.

Laboratory studies of sputum (sputum cytology), blood, urine, and stool can detect abnormalities that may indicate cancer. Sputum cytology is a test in which the phlegm that is coughed up from the lungs is microscopically examined. It is often used to detect lung cancer. Many blood tests used for cancer detection are typically easy to perform. The blood sample is obtained by a lab technician or a doctor by inserting a needle into a vein and is relatively painless. Blood tests can be either specific or non-specific. Often, in certain cancers, the cancer cells release particular proteins (called tumor markers) and blood tests can be used to detect the presence of these tumor markers. However, with a few exceptions, tumor markers are not used for routine screening of cancers, because several non-cancerous conditions also produce positive results. Blood tests are generally more useful in monitoring the effectiveness of the treatment, or in following the course of the disease and detecting recurrent disease.

Imaging tests such as computed tomography scans (CT scans), magnetic resonance imaging (MRI), ultra-sound, and fiberoptic scope examinations help the doctors determine the location of the tumor even if it is deep within the body. Conventional x rays are often used for initial evaluation because they are relatively cheap, painless, and easily accessible. In order to increase the information obtained from a conventional x ray, air or a dye (such as barium or iodine) may be used as a contrast medium to outline or highlight parts of the body.

The most definitive diagnostic test is the biopsy, wherein a piece of tissue is 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.

Screening examinations conducted regularly by healthcare professionals can result in the detection of cancers of the breast, colon, rectum, cervix, prostate, testis, tongue, mouth, and skin at early stages, when treatment is more likely to be successful. Some of the routine screening tests recommended by the ACS are sigmoidoscopy (for colorectal cancer), mammography (for breast cancer), pap smear (for cervical cancer), and the PSA test (for prostate cancer). Self-examinations for cancers of the breast, testis, mouth, and skin can also help in detecting the tumors before the symptoms become serious.

A revolution in molecular biology and cancer genetics has contributed a great deal to the development of several tests designed to assess the risk of getting cancers. These new techniques include genetic testing, in which molecular probes are used to identify mutations in certain genes that have been linked to particular cancers. As of 2009, however, there remain some limitations to genetic testing and its utility appeared ambiguous, emphasizing the need to develop better strategies for early detection.

Treatment

Treatment and prevention of cancers continues to be the focus of a great deal of research as of 2010. Research into new cancer therapies includes cancer-targeting gene therapy, cancer vaccines, and other targeted therapies such as monoclonal antibodies. Most new therapies take years of clinical testing and research.

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 treat-ment should be aimed at relieving the symptoms and controlling the cancer for as long as possible.

Cancer treatment can take many different forms, and is typically tailored to the individual patient. The decision as to which type of treatment is the most appropriate depends on the type and location of cancer, the extent to which it has already spread, the patient’s age, sex, general health status, and personal treatment preferences. The major types of treatment are: surgery, radiation, chemotherapy, biological therapy, targeted therapy, hormone therapy, and bone-marrow and stem cell transplantation.

Surgery

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/or confined to one area of the body.

Surgery can be used for many purposes:

  • Treatment. Treatment of cancer by surgery involves removal of the tumor to cure the disease. This is typically done when the cancer is localized to a discrete area. Along with the cancer, some part of the normal surrounding tissue is also removed to ensure that no cancer cells remain in the area. Since cancer usually spreads via the lymphatic system, adjoining lymph nodes may be examined and sometimes are removed as well.
  • Preventive surgery. Preventive or prophylactic surgery involves removal of an abnormal looking area that is likely to become malignant over time. For example, 40% of people with a colon disease known as ulcerative colitis ultimately die of colon cancer. Rather than live with the fear of developing colon cancer, these people may choose to have the colon removed which reduces the risk of developing colon cancer significantly.
  • Diagnostic purposes. The most definitive tool for diagnosing cancer is a biopsy. Sometimes, a biopsy can be performed by inserting a needle through the skin. However, at other times, the only way to obtain a tissue sample for biopsy is by performing a surgical operation.
  • Cytoreductive surgery is a procedure in which the doctor removes as much of the cancer as possible and then treats the remaining area with radiation therapy or chemotherapy or both.
  • Palliative surgery is aimed at minimizing symptoms associated with cancer. Usually, in such cases, the tumor is so large or has spread so much that removing the entire tumor is not an option. For example, a tumor in the abdomen may be so large that it may press on and block a portion of the intestine, interfering with digestion and causing pain and vomiting.
  • Debulking surgery can be used to remove a part of the blockage and to relieve associated symptoms. In tumors that are dependent on hormones, removal of the organs that secrete the hormones is an option. For example, in prostate cancer, the release of testosterone by the testicles stimulates the growth of cancerous cells. Hence, a man may undergo an orchidectomy (removal of testicles) to slow the progress of the disease. Similarly, in a type of aggressive breast cancer, removal of the ovaries (oophorectomy) stops the synthesis of hormones from the ovaries and may slow the progression of the cancer.

Radiation therapy

Radiation kills tumor cells. Radiation is used alone in cases in which a tumor is unsuitable for surgery. More often, it is used in conjunction with surgery and 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.

Cancer Chemotherapy

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 given in many forms. The most common administration methods include oral (by mouth) or intravenous administration. Chemotherapy may be given alone or in conjunction with surgery, radiation, or both.

When chemotherapy is used before surgery or radiation, it is known as primary chemotherapy or neoadjuvant chemotherapy. An advantage of neoadjuvant chemotherapy is that since the cancer cells have not been exposed to anti-cancer drugs, they are especially vulnerable. It can, therefore, be used effectively to reduce the size of the tumor for surgery or target it for radiation. The more common use of chemotherapy is adjuvant therapy, which is given to enhance the effectiveness of other treatments. For example, after surgery, adjuvant chemotherapy is given to destroy any cancerous cells that still remain in the body.

Biological and targeted therapies

Biological and targeted therapies use the body’s own immune system to destroy cancer cells. As of 2009, this form of treatment was being intensively studied in clinical trials. Many newer agents are used to treat a variety of cancers. The various agents being tested in clinical trials and used as treatment modalities 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 vaccines work by boosting the body’s immune system and training the immune cells to specifically destroy cancer cells.

Hormone therapy

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. Hor- mone therapy involves blocking the production or action of these hormones. As a result, the growth of the tumor slows, and survival may be extended.

Bone marrow, stem cell, and cord blood transplantation

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. 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 someone else. Bone-marrow transplantation, while not a therapy in itself, is often used to ‘‘rescue’’ patients, by allowing those with cancer to undergo aggressive therapy. Stem cell transplants have been performed to replace bone marrow that has been destroyed by cancer, chemotherapy, or radiation therapy. Stem cells are specialized cells in the bone marrow from which the body receives a constant source of blood cells. Stem cells may also be harvested from umbilical cords, a process that is referred to as a cord blood transplant. Some cancers in which stem cell transplants may be used include leukemia, lymphoma, and multiple myeloma.

Alternative treatment

There are a multitude of alternative treatments available to help the person with 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.

Although the effectiveness of complementary therapies such as acupuncture in alleviating cancer pain has not been clinically proven, many cancer patients find it safe and beneficial. Bodywork therapies such as massage and reflexology ease muscle tension and may alleviate side effects such as nausea and vomiting. Homeopathy and herbal remedies used in Chinese traditional herbal medicine also have been shown to alleviate some of the side effects of radiation and chemotherapy and are recommended by many doctors.

Certain foods, including many vegetables, fruits, and grains, are believed to offer protection against various cancers. However, isolation of the individual constituent of vegetables and fruits that are anti-cancer agents has proven difficult. In laboratory studies, vitamins such as A, C, and E, as well as compounds such as isothiocyanates and dithiolthiones found in broccoli, cauliflower, and cabbage, and beta-carotene found in carrots have been shown to protect against cancer. Studies have shown that eating a diet rich in fiber as found in fruits and vegetables reduces the risk of colon cancer. Exercise and a low fat diet help control weight and reduce the risk of endometrial, breast, and colon cancer.

Cancer treatment team

Many different specialists generally work together as a team to treat cancer patients. 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 the primary physician and coordinates the patient’s treatment plan.

The radiation oncologist specializes in using radia-tion to treat cancer, whereas the surgical oncologist per-forms the operations needed to diagnose or treat cancer. Gynecologist-oncologists and pediatric-oncologists, as their titles suggest, are physicians involved with treating women’s and children’s cancers, respectively. Many other specialists also may be involved in the care of a cancer patient. For example, radiologists specialize in the use of x rays, ultrasounds, CT scans, MRI imaging and other techniques that are used to diagnose cancer. Hematologists specialize in disorders of the blood and are consulted in case of blood cancers and bone marrow cancers. The samples that are removed for biopsy are sent to a laboratory, where a pathologist examines them to determine the type of cancer and extent of the disease. There are many other specialties, and virtually any type of medical or surgical specialist may become involved with care of the cancer patient should it become necessary.

Prognosis

Lifetime risk is the phrase that cancer researchers use to refer to the probability that an individual over the course of a lifetime will develop cancer or die from it. In the United States, men have a one in two lifetime risk of developing cancer, and for women the risk is one in three. Overall, African Americans are more likely to develop cancer than whites. African Americans are also 30% more likely to die of cancer than whites.

Many cancers are curable if detected and treated in their early stages. A cancer patient’s prognosis is affected by many factors, particularly the type of cancer the patient has, the stage of the cancer, the extent to which it has metastasized, and the aggressiveness of the cancer. In addition, the patient’s age, general health status, and the effectiveness of the treatment being pursued are important factors.

To help predict the future course and outcome of the disease and the likelihood of recovery from the disease, doctors often use statistics. The five-year survival rates are the most common measures used. The number refers to the proportion of people with cancer who are expected to be alive five years after initial diagnosis compared with a similar population that is free of cancer. It is important to note that while statistics can give some information about the average survival experience of cancer patients in a given population, they cannot be used to indicate individual prognosis because no two patients are exactly alike.

Prevention

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 30 minutes on 5 or more days every week. Forty-five to sixty minutes of moderate to vigorous physical activity is preferable.
  • 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 sun’s rays are the strongest
  • avoiding risky sexual practices
  • avoiding known carcinogens in the environment or work place

Resources

Books

Bradbury, Robert H, ed. Cancer. New York: Springer, 2007.

Geffen, Jeremy R. The Journey through Cancer: Healing and Transforming the Whole Person. New York: Three Rivers Press, 2006.

Visel, Dave. Living with Cancer: A Practical Guide. New Brunswick, NJ: Rutgers University Press, 2006.

Weinberg, Robert A. The Biology of Cancer. New York: Garland Science, 2007.

Periodicals

Jemal, A., Siegel, R., Ward, E., et al. ‘‘Cancer Statistics 2009.’’ CA: A Cancer Journal for Clinicians 59(2009): 225–249.

Organisations

American Cancer Society, 250 Williams Street, Atlanta, GA, 30303-1002, (800) ACS-2345, http://www.cancer.gov. National Cancer Institute, 6116 Executive Blvd., Room 3036A, Bethesda, MD, 20892-8322, (800) 422-6237, http://www.cancer.gov

National Coalition for Cancer Survivorship, 1010 Wayne Avenue, 5th Floor, Suite 300, Silver Spring, MD, 20910, (888) 650-9127, http://www.canceradvocacy.org