Cancer (General)



Cancer develops when cells in a part of the body begin to grow out of control. Although there are many kinds of cancer, they all start because of out-of-control growth of abnormal cells.

Normal body cells grow, divide, and die in an orderly fashion. During the early years of a person's life, normal cells divide more rapidly until the person becomes an adult. After that, cells in most parts of the body divide only to replace worn-out or dying cells and to repair injuries.

Because cancer cells continue to grow and divide, they are different from normal cells. Instead of dying, they outlive normal cells and continue to form new abnormal cells.

Cancer cells develop because of damage to DNA. This substance is in every cell and directs all activities. Most of the time when DNA becomes damaged the body is able to repair it. In cancer cells, the damaged DNA is not repaired. People can inherit damaged DNA, which accounts for inherited cancers. More often, though, a person's DNA becomes damaged by exposure to something in the environment, like smoking.

Cancer usually forms as a tumor. Some cancers, like leukemia, do not form tumors. Instead, these cancer cells involve the blood and blood-forming organs and circulate through other tissues where they grow.

Often, cancer cells travel to other parts of the body where they begin to grow and replace normal tissue. This process is called metastasis. Regardless of where a cancer may spread, however, it is always named for the place it began. For instance, breast cancer that spreads to the liver is still called breast cancer, not liver cancer.

Not all tumors are cancerous. Benign (noncancerous) tumors do not spread (metastasize) to other parts of the body and, with very rare exceptions, are not life threatening.

Different types of cancer can behave very differently. For example, lung cancer and breast cancer are very different diseases. They grow at different rates and respond to different treatments. That is why people with cancer need treatment that is aimed at their particular kind of cancer.

Cancer is the second leading cause of death in the United States. Half of all men and one third of all women in the United States will develop cancer during their lifetimes. Today, millions of people are living with cancer or have had cancer. The risk of developing most types of cancer can be reduced by changes in a person's lifestyle, for example, by quitting smoking and eating a better diet. The sooner a cancer is found and treatment begins, the better are the chances for living for many years.

Signs and Symptoms

It is important to know what some of the general (non-specific) signs and symptoms of cancer are. They include unexplained weight loss, fever, fatigue, pain, and changes in the skin. Of course, it’s important to remember that having any of these does not necessarily mean that cancer is present -- there are many other conditions that can cause these signs and symptoms as well.

Unexplained weight loss: Most people with cancer will lose weight at some time with their disease. An unexplained (unintentional) weight loss of 10 pounds or more may be the first sign of cancer, particularly cancers of the pancreas, stomach, esophagus, or lung.

Fever: Fever is very common with cancer, but is more often seen in advanced disease. Almost all patients with cancer will have fever at some time, particularly if the cancer or its treatment affects the immune system and reduces resistance to infection. Less often, fever may be an early sign of cancer, such as with leukemia or lymphoma.

Fatigue: Fatigue may be a significant symptom as cancer progresses. It may occur early, however, in cancers such as with leukemia or if the cancer is causing a chronic loss of blood, as in some colon or stomach cancers.

Pain: Pain may be an early symptom with some cancers, such as bone cancers or testicular cancer. Most often, however, pain is a symptom of advanced disease.

Skin changes: In addition to cancers of the skin (see next section), some internal cancers can produce visible skin signs such as darkening (hyperpigmentation), yellowing (jaundice), reddening (erythema), itching, or excessive hair growth.

Specific Cancer Signs and Symptoms

In addition to the above general symptoms, you should be watchful for the following common symptoms, which could be an indication of cancer. Again, there may be other causes for each of these, but it is important to bring them to your doctor’s attention as soon as possible so that they can be investigated.

Change in bowel habits or bladder function: Chronic constipation, diarrhea, or a change in the size of the stool may indicate colon cancer. Pain with urination, blood in the urine, or a change in bladder function (such as more frequent or less frequent urination) could be related to bladder or prostate cancer. Any changes in bladder or bowel function should be reported to your doctor.

Sores that do not heal: Skin cancers may bleed and resemble sores that do not heal. A persistent sore in the mouth could be an oral cancer and should be dealt with promptly, especially in patients who smoke, chew tobacco, or frequently drink alcohol. Sores on the penis or vagina may either be signs of infection or an early cancer, and should not be overlooked in either case.

Unusual bleeding or discharge: Unusual bleeding can occur in either early or advanced cancer. Blood in the sputum (phlegm) may be a sign of lung cancer. Blood in the stool (or a dark or black stool) could be a sign of colon or rectal cancer. Cancer of the cervix or the endometrium (lining of the uterus) can cause vaginal bleeding. Blood in the urine is a sign of possible bladder or kidney cancer. A bloody discharge from the nipple may be a sign of breast cancer.

Thickening or lump in breast or other parts of the body: Many cancers can be felt through the skin, particularly in the breast, testicle, lymph nodes (glands), and the soft tissues of the body. A lump or thickening may be an early or late sign of cancer. Any lump or thickening should be reported to your doctor, especially if you’ve just discovered it or noticed it has grown in size. You may be feeling a lump that is an early cancer that could be treated successfully.

Indigestion or trouble swallowing: While they commonly have other causes, these symptoms may indicate cancer of the esophagus, stomach, or pharynx (throat).

Recent change in a wart or mole: Any change in color or shape, loss of definite borders, or an increase in size should be reported to your doctor without delay. The skin lesion may be a melanoma which, if diagnosed early, can be treated successfully.

Nagging cough or hoarseness: A cough that does not go away may be a sign of lung cancer. Hoarseness can be a sign of cancer of the larynx (voice box) or thyroid.

While the signs and symptoms listed above are the more common ones seen with cancer, there are many others that are less common and are not listed here. If you notice any major changes in the way your body functions or the way you feel, especially if it lasts for a long time or gets worse, let your doctor know. If it has nothing to do with cancer, your doctor can investigate it and treat it, if needed. If it is cancer, you’ll give yourself the best chance to have it treated early, when treatment is most likely to be effective.


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Causes

Some kinds of cancer are caused by things people do. Smoking can cause cancers of the lungs, mouth, throat, bladder, kidneys and several other organs, as well as heart disease and stroke. While not everyone who smokes will get cancer, smoking increases a person's chance of getting the disease. Drinking a lot of alcohol has also been shown to increase a person's chance of getting cancer of the mouth, throat, and some other organs. This is especially true if the person drinks and smokes.

Radiation (x-rays) can cause cancer. But the x-rays used by the doctor or dentist are safe. Too much exposure to sunlight without any protection can cause skin cancer.

In many cases, the exact cause of cancer remains a mystery. We know that certain changes in our cells can cause cancer to start, but we don't yet know exactly how this happens. Many scientists are studying this problem.

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Risk Factors

A risk factor is anything that increases a person's chance of getting a disease. Some risk factors can be changed, and others cannot. Risk factors for cancer can include a person's age, sex, and family medical history. Others are linked to cancer-causing factors in the environment. Still others are related to lifestyle choices such as tobacco and alcohol use, diet, and sun exposure.

Having a risk factor for cancer means that a person is more likely to develop the disease at some point in their lives. However, having one or more risk factors does not necessarily mean that a person will get cancer. Some people with one or more risk factors never develop the disease, while other people who do develop cancer have no apparent risk factors. Even when a person who has a risk factor is diagnosed with cancer, there is no way to prove that the risk factor actually caused the cancer.

Different kinds of cancer have different risk factors. Some of the major risk factors include the following:

  • Cancers of the lung, mouth, larynx, bladder, kidney, cervix esophagus, and pancreas are related to tobacco use, including cigarettes, cigars, chewing tobacco, and snuff. Smoking alone causes one-third of all cancer deaths.
  • Skin cancer is related to unprotected exposure to strong sunlight.
  • Breast cancer risk factors include several factors: age; changes in hormone levels throughout life, such as age at first menstruation, number of pregnancies, and age at menopause; obesity; and physical activity. Some studies have also shown a connection between alcohol consumption and an increased risk of breast cancer. Also, women with a mother or sister who have had breast cancer are more likely to develop the disease themselves.
  • While all men are at risk for prostate cancer, several factors can increase the chances of developing the disease, such as age, race, and diet. The chance of getting prostate cancer goes up with age. Prostate cancer is more common among African-American men than among white men. (We do not yet know why this is so.) A high-fat diet may play a part in causing prostate cancer. Also, men with a father or brother who have had prostate cancer are more likely to get prostate cancer themselves.

Overall, environmental factors, defined broadly to include tobacco use, diet, and infectious diseases, as well as chemicals and radiation cause an estimated 75% of all cancer cases in the United States. Among these factors, tobacco use, unhealthy diet, and physical activity are more likely to affect personal cancer risk. Research shows that about one-third of all cancer deaths are related to dietary factors and lack of physical activity in adulthood.

Certain cancers are related to viral infections and could be prevented by behavior changes or vaccines. More than 1 million skin cancers expected to be diagnosed in 2003 could have been prevented by protection from the sun's rays

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Remission

Remission is a period of time when the cancer is responding to treatment or is under control. In a complete remission, all the signs and symptoms of the disease disappear. It is also possible for a patient to have a partial remission in which the cancer shrinks but does not completely disappear. Remissions can last anywhere from several weeks to many years. Complete remissions may continue for years and be considered cures. If the disease returns, another remission often can occur with further treatment. A cancer that has recurred may respond to a different type of therapy, including a different drug combination.

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Treatment

The number of treatment choices you have will depend on the type of cancer, the stage of the cancer, and other individual factors such as your age, health status, and personal preferences. You are a vital part of your cancer care team - you should discuss with them which treatment choices are best for you. Don't be afraid to ask as many questions as you have. Make sure you understand your options. A cancer diagnosis usually gives people a sense of urgency in making choices about treatment and services. However, take the time to consider all the options available to you so you will be as well informed as possible.

The four major types of treatment for cancer are surgery, radiation, chemotherapy, and biologic therapies. You might also have heard about hormone therapies such as tamoxifen and transplant options such as those done with bone marrow.

    Palliative versus Curative Goals: Before starting treatment, ask about the goal of treatment. Is the purpose of the treatment to cure the cancer, control it, or treat symptoms? Sometimes the goal of treatment can change.

    Biologic Therapies

    There is a lot of evidence that suggests that the immune system, the body's natural defense mechanism, plays a major role in the body's response to cancer. At least some forms of cancer occur when the immune system fails to destroy cancer cells or to prevent their growth. Biologic therapy is an effective treatment for certain cancers. It is sometimes called immunotherapy, biotherapy, or biological response modifier therapy. Biologic therapies use the body's immune system to fight cancer or to lessen the side effects of some cancer treatments.

    Biologic therapies can act in several ways in cancer treatment. These include interfering with cancer cell growth, acting indirectly to help healthy immune cells control cancer, and helping to repair normal cells damaged by other forms of cancer treatment.

    There are several kinds of biologic therapy now in use. More than one kind of biologic therapy may be used, or biologic therapy may be combined with chemotherapy or radiation therapy to treat cancer.

    Chemotherapy

    While surgery and radiation therapy are used to treat localized cancers, chemotherapy is used to treat cancer cells that have metastasized (spread) to other parts of the body. Depending on the type of cancer and its stage of development, chemotherapy can be used to cure cancer, to keep the cancer from spreading, to slow the cancer's growth, to kill cancer cells that may have spread to other parts of the body, or to relieve symptoms caused by cancer.

    Chemotherapy is treatment with powerful medicines that are most often given by mouth or by injection. Unlike radiation therapy or surgery, chemotherapy drugs can treat cancers that have spread throughout the body, because they travel throughout the body in the bloodstream. Often, a combination of chemotherapy is used instead of a single drug.

    Chemotherapy is given in cycles, each followed by a recovery period. The total course of chemotherapy is often about six months, usually ranging from three to nine months. After a cancer is removed by surgery, chemotherapy can significantly reduce the risk of cancer returning. The chances of cancer returning and the potential benefit of chemotherapy depend on the type of cancer and other individual factors.

    Side effects of chemotherapy

    Side effects of chemotherapy depend on the type of drugs, the amounts taken, and the length of treatment. The most common are nausea and vomiting, temporary hair loss, increased chance of infections, and fatigue. Many of these side effects can be uncomfortable or emotionally upsetting. However, most side effects can be controlled with medicines, supportive care measures, or by changing the treatment schedule. If you experience side effects, ask your doctor about ways to help ease or eliminate them. Also, keep your doctor informed of all side effects that you experience, as some may require immediate medical attention.

    Fatigue is one of the most common side effects of radiation and chemotherapy. Like most other side effects, it will disappear once the treatment is complete. You can help yourself by getting enough rest, eating a well-balanced diet, drinking plenty of liquids, and by planning your activities to include frequent rest periods.

    Though it is not medically harmful, hair loss can be an upsetting side effect. Most people feel that their hairstyle is a part of their identity, so it is only normal that hair loss is distressing. Some people experience hair loss during chemotherapy treatments (and sometimes with radiation treatment to the head) while others do not, even with the same drugs. Not all drugs cause hair loss. When it does occur, the hair almost always grows back after the treatments are completed. If hair loss does occur, it usually begins within two weeks of the start of therapy and gets worse 1-2 months after the start of therapy. Hair regrowth often begins even before therapy is completed. Most people are able to find suitable ways of managing the hair loss until it grows back, with specially designed hats, scarves, and wigs.

    People having chemotherapy sometimes become discouraged about the length of time their treatment is taking or the side effects they are having. If that happens to you, talk to your doctor. There are ways to reduce the side effects or make them easier to manage. Keep in mind that the expected benefits of the treatment should outweigh any problems you might have because of it.

    Cancer Pain

    Pain is one of the reasons people fear cancer so much. If someone you know has cancer, it is normal to be afraid of witnessing pain. In fact, there are some cancers, which cause no physical pain at all. When it does occur, cancer pain can happen for a variety of reasons. Some people have pain as a result of the growth of a tumor or as a result of advanced cancer, while others may experience pain as a result of treatment side effects.

    You should also know that doctors can treat and manage cancer pain with modern techniques and medicines. A great deal of progress has been made in pain control, so pain can be reduced or alleviated in almost all cases. Even patients with advanced disease can be kept comfortable.

    You may also be concerned that someone taking pain medication for cancer will become addicted to the medication. However, all evidence shows that people who take prescribed drugs for cancer pain do not become addicted. In addition, some methods of pain reduction, such as acupuncture and guided imagery, do not involve drugs.
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Information obtained from National Institute of Health
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