Colon and Rectum Cancer

 

¿What Is Colorectal Cancer??

El cáncer colorrectal es un término que se usa para referirse al cáncer que se desarrolla en el colon o el recto.  El cáncer colorrectal se origina en el sistema digestivo, al que también se le conoce como sistema GI (gastrointestinal). Es aquí donde se procesan los alimentos para generar energía y eliminar del cuerpo el material de desecho sólido (heces fecales).

The normal digestive system

Colon and rectal cancers begin in the digestive system, also called the GI (gastrointestinal) system (see the picture below). This is where food is processed to create energy and rid the body of solid waste matter (stool). In order to understand colorectal cancer, it helps to know some basics about the normal structure and function of the digestive system.
After food is chewed and swallowed, it travels down to the stomach. There it is partly broken down and sent to the small intestine. The word "small" refers to the width of the small intestine. In fact, the small intestine is the longest part of the digestive system -- about 20 feet.



The small intestine also breaks down the food and absorbs most of the nutrients. The small intestine leads to the large intestine (also called the large bowel or colon), a muscular tube about 5 feet long. The colon absorbs water and nutrients from the food and also serves as a storage place for waste matter. The waste matter moves from the colon into the rectum, the last 6 inches of the digestive system. From there the waste passes out of the body through the opening called the anus.

The wall of the colon and rectum has several layers of tissues. Colorectal cancer starts in the inner layer and can grow through some or all of the other layers. Knowing a little about these layers is helpful because the stage (extent of spread) of a cancer depends to a great degree on how deep the cancer goes into these layers.

Abnormal growths in the colon or rectum

Cancer that starts in these different areas may cause different symptoms. But colon cancer and rectal cancer have many things in common. In most cases, colorectal cancers develop slowly over many years. We now know that most of these cancers begin as a polyp--a growth of tissue that starts in the lining and grows into the center of the colon or rectum. This tissue may or may not be cancer. A type of polyp known as an adenoma can become cancerous. Removing a polyp early may prevent it from becoming cancer.
Over 95% of colon and rectal cancers are adenocarcinomas. These are cancers that start in the cells that line the inside of the colon and rectum. There are some other, more rare, types of tumors of the colon and rectum, but the facts given here refer only to adenocarcinomas.

What Causes Colorectal Cancer?

While we do not know the exact cause of most colorectal cancers, there are certain known risk factors. A risk factor is something that affects a person's chance of getting a disease. Some risk factors, like smoking, can be controlled. Others, such as a person's age, can't be changed.
But risk factors don't tell us everything. Having a risk factor, or even several risk factors, does not mean that you will get the disease. And some people who get the disease may not have any known risk factors. Even if a person with colorectal cancer has a risk factor, it is often very hard to know what part that risk factor may have contributed to the cancer.
Researchers have found several risk factors that may increase a person's chance of getting polyps or colorectal cancer.

Risk factors you cannot change

Age:

The chances of having colorectal cancer go up after age 50. More than 9 out of 10 people found to have colorectal cancer are older than 50.

Having had polyps or colorectal cancer before:

Some types of polyps increase the risk of colorectal cancer, especially if they are large or if there are many of them. If you have had colorectal cancer (even if it has been completely removed), you are more likely to have new cancers start in other areas of your colon and rectum. The chances of this happening are greater if you had your first colorectal cancer when you were younger than age 60.

Having a history of bowel disease:

Two bowel diseases, called ulcerative colitis and Crohn’s disease, increase the risk of colon cancer. In these diseases, the colon is inflamed over a long period of time. If you have either of these diseases your doctor may want you to have colon screening testing more often. (These diseases are different than irritable bowel syndrome (IBS), which does not carry an increased risk for colorectal cancer).

Family history of colorectal cancer:

If you have close relatives who have had this cancer, your risk might be increased. This is especially true if the family member got the cancer before age 60. People with a family history of colorectal cancer should talk to their doctors about when and how often to have screening tests.

Certain family syndromes:

A syndrome is a group of symptoms. For example, in some families members tend to get a type of syndrome called FAP that involves having hundreds of polyps in their colon or rectum. Cancer often develops in 1 or more of these polyps.
If your doctor tells you that you have a condition that makes you or your family members more likely to get colorectal cancer, you will probably need to begin colon cancer testing at a younger age and you might want to talk about genetic counseling.

Race or ethnic background:

Some racial and ethnic groups such as African Americans and Jews of Eastern European descent (Ashkenazi Jews) have a higher colorectal cancer risk. All of the reasons for this are not yet understood.

Risk factors linked to things you do

Several lifestyle-related factors have been linked to colorectal cancer. In fact, the links between diet, weight, and exercise and colorectal cancer risk are some of the strongest for any type of cancer.

Certain types of diets:

A diet that is high in red meats (beef, lamb, or liver) and processed meats such as hot dogs, bologna, and lunch meat can increase your colorectal cancer risk. Cooking meats at very high heat (frying, broiling, or grilling) can create chemicals that might increase cancer risk. Diets high in vegetables and fruits have been linked with a lower risk of colorectal cancer.

Lack of exercise:

Getting more exercise may help reduce your risk.

Overweight:

Being very overweight increases a person's risk of dying from colorectal cancer.

Smoking: Most people know that smoking causes lung cancer, but long-time smokers are more likely than non-smokers to die of colorectal cancer. Smoking increases the risk of many other cancers, too.

Alcohol:

Heavy use of alcohol has been linked to colorectal cancer.

Diabetes:

People with type 2 diabetes have an increased chance of getting colorectal cancer. They also tend to have a higher death rate from this cancer.

Risk factors that are less certain

Night-shift work:

One study suggests that working a night shift at least 3 nights a month for at least 15 years might increase the risk of colorectal cancer in women. More research is needed to check out this finding.

Other cancers and their treatment:

A recent report on testicular cancer survivors found that these men had a higher rate of colorectal cancer. Men who receive radiation therapy for prostate cancer have been reported to have a higher risk of rectal cancer, too.
The American Cancer Society and several other medical organizations recommend earlier testing for people with increased colorectal cancer risk. These recommendations differ from those for people at average risk. For more information, talk with your doctor.

Can Colorectal Cancer Be Prevented?

Even though we don't know exactly what causes colorectal cancer, there are some steps you can take to reduce your risk.

Screening tests:

Regular colorectal cancer screening or testing is one of the best ways to help prevent colorectal cancer. Some polyps, or growths, can be found and removed before they have the chance to turn into cancer. Screening can also help find colorectal cancer early, when it is more likely to be cured..
People who have a history of colorectal cancer in their family should check with their doctor for advice about when and how often to have screening tests.

Genetic testing, screening, and treatment for those with a strong family history

People with a strong family history of colorectal polyps or cancer should think about getting genetic counseling to help them decide whether genetic testing or earlier screening may be right for them.

Diet and exercise:

People can lower their risk of getting colorectal cancer by taking charge of the risk factors that they can control, such as diet and exercise. It is important to eat plenty of fruits, vegetables, and whole grain foods and to limit intake of high-fat foods. Getting enough exercise is also important. The American Cancer Society recommends at least 30 minutes of physical activity on 5 or more days of the week. Forty-five to 60 minutes of exercise on 5 or more days of the week is even better.

Vitamins:

Some studies suggest that taking a daily multivitamin containing folic acid or folate can lower colorectal cancer risk. Other studies suggest that getting more calcium and vitamin D can help. One recent study suggested that a diet high in magnesium may also reduce colorectal cancer risk in women. But not all studies have found these supplements to reduce risk. More research is needed in this area.

Aspirin and other drugs:

Aspirin and drugs such as ibuprofen (Motrin, Advil) or naproxen (Aleve), appear to prevent the growth of polyps. A drug called Celebrex also reduces polyps for some people with FAP. But these medicines can have serious or even life-threatening side effects such as stomach bleeding. For this reason, experts do not advise the general public to take them to try to prevent colorectal cancer. If you are at high risk for colorectal cancer, talk to your doctor about what you should do.

Female hormones:

Hormone replacement therapy (HRT) in women after menopause may reduce their risk of getting colorectal cancer. But those women on HRT who do get colorectal cancer may have a fast growing cancer. The decision to use HRT should be based on a careful discussion of benefits and risks with your doctor.

How Is Colorectal Cancer Treated?

This information represents the views of the doctors and nurses serving on the American Cancer Society's Cancer Information Database Editorial Board. These views are based on their interpretation of studies published in medical journals, as well as their own professional experience.
The treatment information in this document is not official policy of the Society and is not intended as medical advice to replace the expertise and judgment of your cancer care team. It is intended to help you and your family make informed decisions, together with your doctor.
Your doctor may have reasons for suggesting a treatment plan different from these general treatment options. Don't hesitate to ask him or her questions about your treatment options.

The 4 main types of treatment for colorectal cancer are :

• surgery 
• radiation therapy 
• chemotherapy (often called just "chemo") 
• targeted therapies (called monoclonal antibodies)

Depending on the stage of your cancer, 2 or more types of treatment may be used at the same time, or used one after the other.
Take your time and think about all of your treatment choices. You may want to get a second opinion. This can give you more information and help you feel better about the treatment plan you choose. Your chances of having a good outcome are highest in the hands of a medical team that has experience in treating colorectal cancer.

Surgery

The types of surgery used to treat colon and rectal cancers are slightly different and are described separately.

Colon surgery

Surgery is often the main treatment for earlier stage colon cancer. The surgery is called a colectomy or a segmental resection. Usually the cancer and a length of normal colon on either side of the cancer (as well as nearby lymph nodes) are removed. The 2 ends of the colon are then sewn back together. For colon cancer, a colostomy (an opening in the abdomen for getting rid of body wastes) is not usually needed, although sometimes a short-term colostomy may be done to allow the colon to heal.
Most often, surgery is done through an incision in the abdomen, but for some earlier stage cancers a different approach might be an option. In laparoscopic-assisted colectomy, instead of 1 long incision in the abdomen, the surgeon makes several small ones. Special long instruments are put into these small openings and used to remove part of the colon and lymph nodes. This method appears to be about as likely to cure the cancer as the standard approach for earlier stage cancers and patients usually recover faster than they do after the usual operations. But the surgery calls for special skill. If you are thinking about this approach, be sure to look for a skilled surgeon who has done a lot of these operations.
Some very early colon cancers (stage 0 and some early stage I tumors) or polyps can be removed using a colonoscope. When this is done, the surgeon does not have to cut into the abdomen. Early stage cancers that are only on the surface of the colon lining can be removed along with a small amount of nearby tissue. For a polypectomy, the cancer is cut out across the base of the polyp's stalk, the area that looks like the stem of a mushroom.

Rectal surgery

Surgery is usually the main treatment for rectal cancer, too, although radiation and chemotherapy will often be given before surgery. There are several types of surgery for rectal cancer.
Some operations (such as polypectomy, local excision, and local transanal resection) can be done with instruments placed into the anus, without having to cut through the skin. One of these methods might be used to remove some stage I cancers that are fairly small and not too far from the anus.
For some stage I, and most stage II or III rectal cancers, other types of surgery may be done.

These are described here:

Low anterior resection:

This approach is used for cancers near the upper part of the rectum, close to where it connects with the colon. The surgeon makes the incision only in the abdomen. Then he removes the cancer and a small amount of normal tissue on either side of the cancer, along with nearby lymph nodes and a large amount of fatty and fibrous tissue around the rectum. The anus is not affected. After the surgery, the colon is reattached to the anus and waste leaves the body in the usual way.

Abdominoperineal (AP) resection:

For cancers in the lower part of the rectum, close to its outer connection to the anus, an abdominoperineal (AP) resection is done. For this the surgeon makes 1 incision in the abdomen, and another in the area around the anus. Because the anus is removed, a colostomy is needed. A colostomy is an opening of the colon in the front of the abdomen. It is used for the body to get rid of solid body waste (feces or stool).

Pelvic exenteration:

If the rectal cancer is growing into nearby organs, more extensive surgery is needed. In a pelvic exenteration the surgeon removes the rectum as well as nearby organs such as the bladder, prostate, or uterus if the cancer has spread to these organs. A colostomy is needed after this operation. If the bladder is removed, a urostomy (an opening to collect urine) is also needed.

Side effects of colorectal surgery

Side effects of surgery depend on several things, such as the extent of the operation and a person's general health before surgery. Most people will have at least some pain after the operation, but this can usually be controlled with medicines if needed. Eating problems usually inprove within a few days of surgery.
Possible side effects of surgery include bleeding from the surgery, blood clots in the legs, and damage to nearby organs during the operation. Rarely, the connections between the ends of the intestine may not hold together completely and leak. If an infection occurs, it is possible that the incision might open up, causing an open wound. Later, after the surgery, you might develop scar tissue in your abdomen (called adhesions) that could cause the bowel to become blocked.
If you have a colostomy or a urostomy, you will need help in learning how to manage it. This can be done by specially trained nurses. They will usually see you before your operation and again afterwards for more training.

Colorectal surgery and sex

If you are a man, an AP resection can cause you to have "dry" orgasms. That is, the feeling of pleasure will most likely still be there, but no semen comes out. In some cases an AP resection may make you unable to have erections or reach orgasm. In other cases your pleasure at orgasm may become less intense. Normal aging may cause some of these changes, but surgery can increase them.
For some men, the surgery causes the semen to go backward into the bladder. This is not harmful. But if you still want to father a child, you should talk to your doctor about how the surgery will affect you and what might be done to achieve a pregnancy.
If you are a woman having colorectal surgery, you should not normally find any loss of sexual function. Scar tissue may sometimes cause pain or discomfort during intercourse. And if the uterus is removed, pregnancy will not be possible.
For men and women, a colostomy can affect your body image and your sexual comfort level. While you may need to make some adjustments, it should not keep you from having an enjoyable sex life.
The American Cancer Society has more information for both men and women about sexuality and cancer. Please see the list of booklets at the end of this article.

Surgery for colorectal cancer that has spread

Sometimes, surgery for cancer that has spread to other organs can help you to live longer or, depending on the extent of the disease, may even cure you. If the colorectal cancer has spread to a few areas in liver or lungs (and nowhere else), the cancer can sometimes be removed by surgery.
For spread to the liver, there are other methods besides surgery which might be used to destroy the cancer. These include methods to block the blood supply to the tumor or to destroy the cancer through freezing or by heating with microwaves. These methods are not meant to cure the cancer.

Radiation therapy for colon and rectal cancer

Radiation therapy is treatment with high-energy rays (such as x-rays) to kill or shrink cancer cells. The radiation may come from outside the body (external radiation) or from radioactive materials placed directly in the tumor (brachytherapy or internal or implant radiation).
After surgery, radiation can kill small areas of cancer that may not be removed during surgery. If the size or location of a tumor makes surgery hard, radiation may be used before the surgery to shrink the tumor. Radiation can also be used to ease symptoms of advanced cancer such as intestinal blockage, bleeding, or pain.
The main use for radiation therapy in people with colon cancer is when the cancer has attached to an internal organ or the lining of the abdomen. If this happens, the doctor can't be sure that all the cancer has been removed, and radiation therapy is used to kill the cancer cells left behind after surgery. For rectal cancer, radiation is also given to prevent the cancer from coming back in the place where it started and to treat local recurrences that are causing symptoms such as pain. Radiation is seldom used to treat metastatic colon cancer.

External-beam radiation therapy:

In this method, radiation is focused on the cancer from a machine outside the body. This approach is most often used for people with colon or rectal cancer. Treatments are given 5 days a week for several weeks. Each treatment lasts only a few minutes although the setup time -- getting you into place for treatment -- usually takes longer.
A different approach may be used for some cases of rectal cancer with small tumors. The radiation can be aimed through the anus and reaches the rectum without passing through the skin of the abdomen. This means it is less likely to damage nearby tissues and cause side effects.

Brachytherapy (internal radiation therapy):

In this method, small pellets or seeds of radioactive material are placed next to or directly into the cancer. The radiation travels only a short distance, limiting the effects on nearby healthy tissues. This method is sometimes used in treating people with rectal cancer, particularly sick or older people who would not be able to withstand surgery.

Side effects of radiation therapy

Side effects of radiation therapy for colon or rectal cancer include mild skin irritation, nausea, diarrhea, trouble controlling your bowel, rectal or bladder irritation, or tiredness. Sexual problems may also occur. Side effects often go away after treatment is over. If you have these or other side effects, talk to your doctor. There are often ways to reduce or relieve many of these problems.

Chemotherapy

Chemotherapy (often called simply "chemo") is the use of drugs to fight cancer. The drugs may be injected into a vein or given by mouth. These drugs enter the bloodstream and spread throughout the body, making the treatment useful for cancers that have spread to distant organs.
Chemo after surgery can increase the survival rate for patients with some stages of colorectal cancer. Chemo can also help relieve symptoms of advanced cancer.
In some cases, chemo drugs can be injected into an artery leading to the part of the body with the tumor. This approach is called regional chemotherapy. Since the drugs go straight to the cancer cells, there may be fewer side effects.

Side effects of chemotherapy

While chemo kills cancer cells, it also damages some normal cells and this can cause side effects. These side effects will depend on the type of drugs given, the amount given, and how long treatment lasts. Side effects could include the following:

• Diarrhea 
• Nausea and vomiting 
• Loss of appetite 
• Hair loss 
• Hand and foot rashes and swelling 
• Mouth sores 
• Increased chance of infection 
• Easy bleeding or bruising after minor cuts or injuries 
• severe tiredness (fatigue)

Most of the side effects go away when treatment is over. For example, hair will grow back after treatment ends, though it may look different. Anyone who has problems with side effects should talk with their doctor or nurse, as there are often ways to help.

Targeted therapies

Targeted therapies are drugs that attack a part of cancer cells that makes them different from normal cells. Because these drugs affect only cancer cells, they often cause fewer side effects than chemo. Man-made proteins called monoclonal antibodies have been approved for use, along with chemo, against colorectal cancer.

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