Cancer affects our cells, the body's basic unit of life. To understand cancer, it is helpful to know what happens when normal cells become cancerous.
The body is made up of many types of cells. Normally, cells grow, divide, and produce more cells as they are needed to keep the body healthy and functioning properly. Sometimes, however, the process goes astray -- cells keep dividing when new cells are not needed. The mass of extra cells forms a growth or tumor. Tumors can be either benign or malignant.
- Benign tumors are not cancer. They often can be removed and, in most cases, they do not come back. Cells in benign tumors do not spread to other parts of the body. Most important, benign tumors are rarely a threat to life.
- Malignant tumors are cancer. Cells in malignant tumors are abnormal and divide without control or order. These cancer cells can invade and destroy the tissue around them. Cancer cells can also break away from a malignant tumor. They may enter the bloodstream or lymphatic system (the tissues and organs that produce and store cells that fight infection and disease). This process, called metastasis, is how cancer spreads from the original (primary) tumor to form new (secondary) tumors in other parts of the body.
The Colon and Rectum
The colon and rectum are parts of the body's digestive system, which removes nutrients from food and stores waste until it passes out of the body. Together, the colon and rectum form a long, muscular tube called the large intestine (also called the large bowel). The colon is the first 6 feet of the large intestine, and the rectum is the last 8 to 10 inches.
Understanding Colorectal Cancer
Cancer that begins in the colon is called colon cancer, and cancer that begins in the rectum is called rectal cancer. Cancers affecting either of these organs may also be called colorectal cancer.
Colorectal Cancer: Who's at Risk?
The exact causes of colorectal cancer are not known. However, studies show that the following risk factors increase a person's chances of developing colorectal cancer:
- Age. Colorectal cancer is more likely to occur as people get older. This disease is more common in people over the age of 50. However, colorectal cancer can occur at younger ages, even, in rare cases, in the teens.
- Diet. Colorectal cancer seems to be associated with diets that are high in fat and calories and low in fiber. Researchers are exploring how these and other dietary factors play a role in the development of colorectal cancer.
- Polyps. Polyps are benign growths on the inner wall of the colon and rectum. They are fairly common in people over age 50. Some types of polyps increase a person's risk of developing colorectal cancer.
A rare, inherited condition, called familial polyposis, causes hundreds of polyps to form in the colon and rectum. Unless this condition is treated, familial polyposis is almost certain to lead to colorectal cancer.
- Personal medical history. Research shows that women with a history of cancer of the ovary, uterus, or breast have a somewhat increased chance of developing colorectal cancer. Also, a person who has already had colorectal cancer may develop this disease a second time.
- Family medical history. First-degree relatives (parents, siblings, children) of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves, especially if the relative had the cancer at a young age. If many family members have had colorectal cancer, the chances increase even more.
- Ulcerative colitis. Ulcerative colitis is a condition in which the lining of the colon becomes inflamed. Having this condition increases a person's chance of developing colorectal cancer.
Risk Factors Associated with Colorectal Cancer
- Personal History
- Family History
- Ulcerative Colitis
Having one or more of these risk factors does not guarantee that a person will develop colorectal cancer. It just increases the chances. People may want to talk with a doctor about these risk factors. The doctor may be able to suggest ways to reduce the chance of developing colorectal cancer and can plan an appropriate schedule for checkups.
Colorectal Cancer: Reducing the Risk
The National Cancer Institute supports and conducts research on the causes and prevention of colorectal cancer. Research shows that colorectal cancer develops gradually from benign polyps. Early detection and removal of polyps may help to prevent colorectal cancer. Studies are looking at smoking cessation, use of dietary supplements, use of aspirin or similar medicines, decreased alcohol consumption, and increased physical activity to see if these approaches can prevent colorectal cancer. Some studies suggest that a diet low in fat and calories and high in fiber can help prevent colorectal cancer.
Researchers have discovered that changes in certain genes (basic units of heredity) raise the risk of colorectal cancer. Individuals in families with several cases of colorectal cancer may find it helpful to talk with a genetic counselor. The genetic counselor can discuss the availability of a special blood test to check for a genetic change that may increase the chance of developing colorectal cancer. Although having such a genetic change does not mean that a person is sure to develop colorectal cancer, those who have the change may want to talk with their doctor about what can be done to prevent the disease or detect it early.
Detecting Cancer Early
People who have any of the risk factors described under "Colorectal Cancer: Who's at Risk?" should ask a doctor when to begin checking for colorectal cancer, what tests to have, and how often to have them. The doctor may suggest one or more of the tests listed below. These tests are used to detect polyps, cancer, or other abnormalities, even when a person does not have symptoms. Your health care provider can explain more about each test.
- A fecal occult blood test (FOBT) is a test used to check for hidden blood in the stool. Sometimes cancers or polyps can bleed, and FOBT is used to detect small amounts of bleeding.
- A sigmoidoscopy is an examination of the rectum and lower colon (sigmoid colon) using a lighted instrument called a sigmoidoscope.
- A colonoscopy is an examination of the rectum and entire colon using a lighted instrument called a colonoscope.
- A double contrast barium enema (DCBE) is a series of x-rays of the colon and rectum. The patient is given an enema with a solution that contains barium, which outlines the colon and rectum on the x-rays.
- A digital rectal exam (DRE) is an exam in which the doctor inserts a lubricated, gloved finger into the rectum to feel for abnormal areas.
- A change in bowel habits
- Diarrhea, constipation, or feeling that the bowel does not empty completely
- Blood (either bright red or very dark) in the stool
- Stools that are narrower than usual
- General abdominal discomfort (frequent gas pains, bloating, fullness, and/or cramps)
- Weight loss with no known reason
- Constant tiredness
- VomitingThese symptoms may be caused by colorectal cancer or by other conditions. It is important to check with a doctor.
Diagnosing Colorectal Cancer
To help find the cause of symptoms, the doctor evaluates a person's medical history. The doctor also performs a physical exam and may order one or more diagnostic tests.
- X-rays of the large intestine, such as the DCBE, can reveal polyps or other changes.
- A sigmoidoscopy lets the doctor see inside the rectum and the lower colon and remove polyps or other abnormal tissue for examination under a microscope.
- A colonoscopy lets the doctor see inside the rectum and the entire colon and remove polyps or other abnormal tissue for examination under a microscope.
- A polypectomy is the removal of a polyp during a sigmoidoscopy or colonoscopy.
- A biopsy is the removal of a tissue sample for examination under a microscope by a pathologist to make a diagnosis.
Stages of Colorectal Cancer
If the diagnosis is cancer, the doctor needs to learn the stage (or extent) of disease. Staging is a careful attempt to find out whether the cancer has spread and, if so, to what parts of the body. More tests may be performed to help determine the stage. Knowing the stage of the disease helps the doctor plan treatment. Listed below are descriptions of the various stages of colorectal cancer.
- Stage 0. The cancer is very early. It is found only in the innermost lining of the colon or rectum.
- Stage I. The cancer involves more of the inner wall of the colon or rectum.
- Stage II. The cancer has spread outside the colon or rectum to nearby tissue, but not to the lymph nodes. (Lymph nodes are small, bean-shaped structures that are part of the body's immune system.)
- Stage III. The cancer has spread to nearby lymph nodes, but not to other parts of the body.
- Stage IV. The cancer has spread to other parts of the body. Colorectal cancer tends to spread to the liver and/or lungs.
- Recurrent. Recurrent cancer means the cancer has come back after treatment. The disease may recur in the colon or rectum or in another part of the body.
Treatment for Colorectal Cancer
Treatment depends mainly on the size, location, and extent of the tumor, and on the patient's general health. Patients are often treated by a team of specialists, which may include a gastroenterologist, surgeon, medical oncologist, and radiation oncologist. Several different types of treatment are used to treat colorectal cancer. Sometimes different treatments are combined.
- Surgery to remove the tumor is the most common treatment for colorectal cancer. Generally, the surgeon removes the tumor along with part of the healthy colon or rectum and nearby lymph nodes. In most cases, the doctor is able to reconnect the healthy portions of the colon or rectum. When the surgeon cannot reconnect the healthy portions, a temporary or permanent colostomy is necessary. Colostomy, a surgical opening (stoma) through the wall of the abdomen into the colon, provides a new path for waste material to leave the body. After a colostomy, the patient wears a special bag to collect body waste. Some patients need a temporary colostomy to allow the lower colon or rectum to heal after surgery. About 15 percent of colorectal cancer patients require a permanent colostomy.
- Chemotherapy is the use of anticancer drugs to kill cancer cells. Chemotherapy may be given to destroy any cancerous cells that may remain in the body after surgery, to control tumor growth, or to relieve symptoms of the disease. Chemotherapy is a systemic therapy, meaning that the drugs enter the bloodstream and travel through the body. Most anticancer drugs are given by injection directly into a vein (IV) or by means of a catheter, a thin tube that is placed into a large vein and remains there as long as it is needed. Some anticancer drugs are given in the form of a pill.
- Radiation therapy, also called radiotherapy, involves the use of high-energy x-rays to kill cancer cells. Radiation therapy is a local therapy, meaning that it affects the cancer cells only in the treated area. Most often it is used in patients whose cancer is in the rectum. Doctors may use radiation therapy before surgery (to shrink a tumor so that it is easier to remove) or after surgery (to destroy any cancer cells that remain in the treated area). Radiation therapy is also used to relieve symptoms. The radiation may come from a machine (external radiation) or from an implant (a small container of radioactive material) placed directly into or near the tumor (internal radiation). Some patients have both kinds of radiation therapy.
- Biological therapy, also called immunotherapy, uses the body's immune system to fight cancer. The immune system finds cancer cells in the body and works to destroy them. Biological therapies are used to repair, stimulate, or enhance the immune system's natural anticancer function. Biological therapy may be given after surgery, either alone or in combination with chemotherapy or radiation treatment. Most biological treatments are given by injection into a vein (IV).
- Clinical trials (research studies) to evaluate new ways to treat cancer are an appropriate option for many patients with colorectal cancer. In some studies, all patients receive the new treatment. In others, doctors compare different therapies by giving the promising new treatment to one group of patients and the usual (standard) therapy to another group.
Research has led to many advances in the treatment of colorectal cancer. Through research, doctors explore new ways to treat cancer that may be more effective than the standard therapy. The NCI publication Taking Part in Clinical Trials: What Cancer Patients Need To Know provides information about how these studies work. PDQ®, NCI's cancer information database, contains detailed information about ongoing studies for colorectal cancer. NCI's Web site includes a section on clinical trials at http://cancer.gov/clinical_trials. This section provides both general information about clinical trials and detailed information about specific ongoing studies for colorectal cancer.
The NCI's Cancer.gov Web site provides information from numerous NCI sources, including PDQ®, NCI's cancer information database. PDQ® contains current information on cancer prevention, screening, diagnosis, treatment, genetics, supportive care, and ongoing clinical trials. Cancer.gov can be accessed at http://www.cancer.gov on the Internet.
** Side Effects of Treatment**
The side effects of cancer treatment depend on the type of treatment and may be different for each person. Most often the side effects are temporary. Doctors and nurses can explain the possible side effects of treatment. Patients should report severe side effects to their doctor. Doctors can suggest ways to help relieve symptoms that may occur during and after treatment.
- Surgery causes short-term pain and tenderness in the area of the operation. Surgery for colorectal cancer may also cause temporary constipation or diarrhea. Patients who have a colostomy may have irritation of the skin around the stoma. The doctor, nurse, or enterostomal therapist can teach the patient how to clean the area and prevent irritation and infection.
- Chemotherapy affects normal as well as cancer cells. Side effects depend largely on the specific drugs and the dose (amount of drug given). Common side effects of chemotherapy include nausea and vomiting, hair loss, mouth sores, diarrhea, and fatigue. Less often, serious side effects may occur, such as infection or bleeding.
- Radiation therapy, like chemotherapy, affects normal as well as cancer cells. Side effects of radiation therapy depend mainly on the treatment dose and the part of the body that is treated. Common side effects of radiation therapy are fatigue, skin changes at the site where the treatment is given, loss of appetite, nausea, and diarrhea. Sometimes, radiation therapy can cause bleeding through the rectum (bloody stools).
- Biological therapy may cause side effects that vary with the specific type of treatment. Often, treatments cause flu-like symptoms, such as chills, fever, weakness, and nausea.
Several useful NCI booklets, including Chemotherapy and You, Radiation Therapy and You, and Eating Hints for Cancer Patients, suggest ways for patients to cope with their side effects during cancer treatment.
The health care team can explain the possible side effects of treatment. Patients should report severe side effects. Doctors and nurses can suggest ways to help relieve symptoms that may occur during and after treatment.
The Importance of Followup Care
Followup care after treatment for colorectal cancer is important. Regular checkups ensure that changes in health are noticed. If the cancer returns or a new cancer develops, it can be treated as soon as possible. Checkups may include a physical exam, a fecal occult blood test, a colonoscopy, chest x-rays, and lab tests. Between scheduled checkups, a person who has had colorectal cancer should report any health problems to the doctor as soon as they appear.
Providing Emotional Support
Living with a serious disease, such as cancer, is challenging. Apart from having to cope with the physical and medical challenges, people with cancer face many worries, feelings, and concerns that can make life difficult. Some people find they need help coping with the emotional as well as the practical aspects of their disease. In fact, attention to the emotional burden of having cancer is often a part of a patient's treatment plan. The support of the health care team (doctors, nurses, social workers, and others), support groups, and patient-to-patient networks can help people feel less alone and upset, and improve the quality of their lives. Cancer support groups provide a setting where cancer patients can talk about living with cancer with others who may be having similar experiences. Patients may want to speak to a member of their health care team about finding a support group. Many also find useful information in NCI fact sheets and booklets, including Taking Time and Facing Forward.
Questions for Your Doctor
This booklet is designed to help you get information you need from your doctor, so that you can make informed decisions about your health care. In addition, asking your doctor the following questions will help you understand your condition better. To help you remember what the doctor says, you may take notes or ask whether you may use a tape recorder. Some people also want to have a family member or friend with them when they talk to the doctor -- to take part in the discussion, to take notes, or just to listen.
- What tests can diagnose colorectal cancer? Are they painful?
- How soon after the tests will I learn the results?
- Are my children or other relatives at higher risk for colorectal cancer?
- What is the stage of my cancer?
- What treatments are recommended for me?
- Should I see a surgeon? Medical oncologist? Radiation oncologist?
- What clinical trials might be appropriate?
- Will I need a colostomy? Will it be permanent?
- What will happen if I don't have the suggested treatment?
- Will I need to be in the hospital to receive my treatment? For how long?
- How might my normal activities change during my treatment?
- After treatment, how often do I need to be checked? What type of followup care should I have?
- What side effects should I expect? How long will they last?
- What side effects should I report? Whom should I call?
The Health Care Team
- Who will be involved with my treatment and rehabilitation? What role will each member of the health care team play in my care?
- What has been your experience in caring for patients with colorectal cancer?
- Are there support groups in the area with people I can talk to?
- Where can I get more information about colorectal cancer?
SOURCE: National Cancer Institute
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