Colorectal cancer(Bowel cancer)

Alternative Names:Bowel cancer,large bowel cancer,colon cancer or “CRC” includes cancerous growths in the colon, rectum and appendix.

What is Cancer?
Cancer is a group of more than 100 different diseases. They affect the body’s basic unit, the cell. Cancer occurs when cells become abnormal and divide without control or order. Like all other organs of the body, the colon and rectum are made up of many types of cells. Normally, cells divide to produce more cells only when the body needs them. This orderly process helps keep us healthy….

If cells keep dividing when new cells are not needed, a mass of tissue forms. This mass of extra tissue, called a growth or tumor, can be benign or malignant.

Benign tumors are not cancer. They can usually be removed and, in most cases, they do not come back. Most important, cells from benign tumors do not spread to other parts of the body. Benign tumors are rarely a threat to life.

Malignant tumors are cancer. Cancer cells can invade and damage tissues and organs near the tumor. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or lymphatic system. This is how cancer spreads from the original (primary) tumor to form new tumors in other parts of the body. The spread of cancer is called metastasis.

When cancer spreads to another part of the body, the new tumor has the same kind of abnormal cells and the same name as the primary tumor. For example, if colon cancer spreads to the liver, the cancer cells in the liver are colon cancer cells. The disease is metastatic colon cancer (it is not liver cancer

Definition :

It is an   Invasive cancers that are confined within the wall of the colon (TNM stages I and II) are curable with surgery. If untreated, they spread to regional lymph nodes (stage III), where up to 73% are curable by surgery and chemotherapy. Cancer that metastasizes to distant sites (stage IV) is usually not curable, although chemotherapy can extend survival, and in rare cases, surgery and chemotherapy together have seen patients through to a cure.[3] Radiation is used with rectal cancer.

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On the cellular and molecular level, colorectal cancer starts with a mutation to the Wnt signaling pathway. When Wnt binds to a receptor on the cell, that sets in motion a chain of molecular events that ends with ß-catenin moving into the nucleus and activating a gene on DNA. In colorectal cancer, genes along this chain are damaged. Usually, a gene called APC, which is a “brake” on the Wnt pathway, is damaged. Without a working APC brake, the Wnt pathway is stuck in the “on” position
Invasive cancers that are confined within the wall of the colon (TNM stages I and II) are curable with surgery. If untreated, they spread to regional lymph nodes (stage III), where up to 73% are curable by surgery and chemotherapy. Cancer that metastasizes to distant sites (stage IV) is usually not curable, although chemotherapy can extend survival, and in rare cases, surgery and chemotherapy together have seen patients through to a cure. Radiation is used with rectal cancer.

On the cellular and molecular level, colorectal cancer starts with a mutation to the Wnt signaling pathway. When Wnt binds to a receptor on the cell, that sets in motion a chain of molecular events that ends with ß-catenin moving into the nucleus and activating a gene on DNA. In colorectal cancer, genes along this chain are damaged. Usually, a gene called APC, which is a “brake” on the Wnt pathway, is damaged. Without a working APC brake, the Wnt pathway is stuck in the “on” position.

Most cases of colon cancer begin as small, noncancerous (benign) clumps of cells called adenomatous polyps. Over time some of these polyps become colon cancers.

Symptoms:
*A change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool for more than a couple of weeks
*Rectal bleeding or blood in your stool
*Persistent abdominal discomfort, such as cramps, gas or pain
*A feeling that your bowel doesn’t empty completely
*Weakness or fatigue
*Unexplained weight loss

Many people with colon cancer experience no symptoms in the early stages of the disease. When symptoms appear, they’ll likely vary, depending on the cancer’s size and location in your large intestine.

Causes:
It’s not very clear what causes colon cancer in most cases. Doctors know that colon cancer occurs when healthy cells in the colon become altered. Healthy cells grow and divide in an orderly way to keep your body functioning normally. But sometimes this growth gets out of control — cells continue dividing even when new cells aren’t needed. In the colon and rectum, this exaggerated growth may cause precancerous cells to form in the lining of your intestine. Over a long period of time — spanning up to several years — some of these areas of abnormal cells may become cancerous.

But doctors are certain that colorectal cancer is not contagious (a person cannot catch the disease from a cancer patient). Some people are more likely to develop colorectal cancer than others. Factors that increase a person’s risk of colorectal cancer include high fat intake, a family history of colorectal cancer and polyps, the presence of polyps in the large intestine, and chronic ulcerative colitis.

Polyps may be small and produce few, if any, symptoms. For this reason, doctors recommend regular screening tests to help prevent colorectal cancer by identifying polyps before they become colorectal cancer.

Risk Factors:
The lifetime risk of developing colon cancer in the United States is about 7%. Certain factors increase a person’s risk of developing the disease. These include:

*Age: The risk of developing colorectal cancer increases with age. Most cases occur in the 60s and 70s, while cases before age 50 are uncommon unless a family history of early colon cancer is present.

*Polyps of the colon, particularly adenomatous polyps, are a risk factor for colon cancer. The removal of colon polyps at the time of colonoscopy reduces the subsequent risk of colon cancer.

*History of cancer. Individuals who have previously been diagnosed and treated for colon cancer are at risk for developing colon cancer in the future. Women who have had cancer of the ovary, uterus, or breast are at higher risk of developing colorectal cancer.

Heredity:
*Family history of colon cancer, especially in a close relative before the age of 55 or multiple relatives.
*Familial adenomatous polyposis (FAP) carries a near 100% risk of developing colorectal cancer by the age of 40 if untreated
*Hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch syndrome
*Gardner syndrome

*Smoking: Smokers are more likely to die of colorectal cancer than nonsmokers. An American Cancer Society study found “Women who smoked were more than 40% more likely to die from colorectal cancer than women who never had smoked. Male smokers had more than a 30% increase in risk of dying from the disease compared to men who never had smoked.”

*Diet: Studies show that a diet high in red meat and low in fresh fruit, vegetables, poultry and fish increases the risk of colorectal cancer. In June 2005, a study by the European Prospective Investigation into Cancer and Nutrition suggested that diets high in red and processed meat, as well as those low in fiber, are associated with an increased risk of colorectal cancer. Individuals who frequently eat fish showed a decreased risk. However, other studies have cast doubt on the claim that diets high in fiber decrease the risk of colorectal cancer; rather, low-fiber diet was associated with other risk factors, leading to confounding. The nature of the relationship between dietary fiber and risk of colorectal cancer remains controversial.

*Lithocholic acid: Lithocholic acid is a bile acid that acts as a detergent to solubilize fats for absorption. It is made from chenodeoxycholic acid by bacterial action in the colon. It has been implicated in human and experimental animal carcinogenesis. Carbonic acid type surfactants easily combine with calcium ion and become detoxication products.

*Physical inactivity: People who are physically active are at lower risk of developing colorectal cancer.
Viruses: Exposure to some viruses (such as particular strains of human papilloma virus) may be associated with colorectal cancer.[citation needed]
Primary sclerosing cholangitis offers a risk independent to ulcerative colitis.
Low levels of selenium.

*Inflammatory bowel disease: About one percent of colorectal cancer patients have a history of chronic ulcerative colitis. The risk of developing colorectal cancer varies inversely with the age of onset of the colitis and directly with the extent of colonic involvement and the duration of active disease. Patients with colorectal Crohn’s disease have a more than average risk of colorectal cancer, but less than that of patients with ulcerative colitis.

*Environmental factors. Industrialized countries are at a relatively increased risk compared to less developed countries that traditionally had high-fiber/low-fat diets. Studies of migrant populations have revealed a role for environmental factors, particularly dietary, in the etiology of colorectal cancers.

*Exogenous hormones. The differences in the time trends in colorectal cancer in males and females could be explained by cohort effects in exposure to some gender-specific risk factor; one possibility that has been suggested is exposure to estrogens. There is, however, little evidence of an influence of endogenous hormones on the risk of colorectal cancer. In contrast, there is evidence that exogenous estrogens such as hormone replacement therapy (HRT), tamoxifen, or oral contraceptives might be associated with colorectal tumors.

*Alcohol: Drinking, especially heavily, may be a risk factor.

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*Vitamin B6 intake is inversely associated with the risk of colorectal cancer.

Diagnosis:
If your signs and symptoms indicate that you could have colon cancer, your doctor may recommend one of more tests and procedures, including:

*Blood tests. Your doctor may order blood tests to better understand what may be causing your signs and symptoms, but there are no blood tests that can detect colon cancer. Blood tests may include a complete blood count and organ-function tests.

*Using a scope to examine the inside of your colon. Colonoscopy uses a long, flexible and slender tube attached to a video camera and monitor to view your entire colon and rectum. If any suspicious areas are found, your doctor can pass surgical tools through the tube to take tissue samples (biopsies) for analysis.

*Using dye and X-rays to make a picture of your colon. A barium enema allows your doctor to evaluate your entire colon with an X-ray. Barium, a contrast dye, is placed into your bowel in an enema form. During a double-contrast barium enema, air also is added. The barium fills and coats the lining of the bowel, creating a clear silhouette of your rectum, colon and sometimes a small portion of your small intestine.

*Using multiple CT images to create a picture of your colon. Virtual colonoscopy combines multiple computerized tomography (CT) images to create a detailed picture of the inside of your colon. If you’re unable to undergo colonoscopy, your doctor may recommend virtual colonoscopy.

Staging colon cancer.
Once you’ve been diagnosed with colon cancer, your doctor will then order tests to determine the extent, or stage, of your cancer. Staging helps determine what treatments are most appropriate for you. Staging tests may include imaging procedures such as abdominal and chest CT scans. In many cases, the stage of your cancer may not be determined until after colon cancer surgery.

The stages of colon cancer are:

*Stage 0. Your cancer is in the earliest stage. It hasn’t grown beyond the inner layer (mucosa) of your colon or rectum. This stage of cancer may also be called carcinoma in situ.
*Stage I. Your cancer has grown through the mucosa but hasn’t spread beyond the colon wall or rectum.
*Stage II. Your cancer has grown into or through the wall of the colon or rectum but hasn’t spread to nearby lymph nodes.
*Stage III. Your cancer has invaded nearby lymph nodes but isn’t affecting other parts of your body yet.
*Stage IV. Your cancer has spread to distant sites, such as other organs — for instance to your liver or lung.
*Recurrent. This means your cancer has come back after treatment. It may recur in your colon, rectum or other part of your body.
Treatment:
The main treatment option for Colorectal cancer  is surgery – if the disease can be caught before it breaks through the bowel wall, chances of success are much higher.

Usually, the piece of bowel that contains the cancer is removed and the two open ends are joined back together. This operation is called a bowel resection.

If the two sections can’t be joined back together, often because the tumour is too low, the bowel can be brought out through the abdominal wall. This is called a stoma, which is connected to a colostomy bag. Although this procedure is more likely after removal of a tumour in the rectum, it isn’t always necessary and may only be temporary. In these cases, further treatment may not be necessary.

Chemotherapy and radiotherapy are increasingly being used to treat bowel cancer in addition to surgery, especially in more advanced tumours. For example, a combination of radiotherapy and chemotherapy may be given before surgery for rectal cancer. This is known as neo-adjuvant therapy and may reduce the risk of recurrence and improve survival rates.

How well patients do after treatment depends on the stage the cancer has reached. Survival rates have improved in the past 30 years, but overall survival is still only about 50 per cent at five years. However, when bowel cancer is caught early – before it has spread to other organs such as the liver or the lungs – the chances of recovery are more than 80 per cent.

Alternative Medication:
No complementary or alternative treatments have been found to cure colon cancer.

Alternative treatments may help you cope with a diagnosis of colon cancer. Nearly all people with cancer experience some distress. Common signs and symptoms of distress after your diagnosis might include sadness, anger, difficulty concentrating, difficulty sleeping and loss of appetite. Alternative treatments may help redirect your thoughts away from your fears, at least temporarily, to give you some relief.

Alternative treatments that may help relieve distress include:

*Art therapy
*Dance or movement therapy
*Exercise
*Meditation
*Music therapy
*Relaxation exercises

Your doctor can refer you to professionals who can help you learn about and try these alternative treatments. Tell your doctor if you’re experiencing distress.

Prognosis:
Survival is directly related to detection and the type of cancer involved, but overall is poor for symptomatic cancers, as they are typically quite advanced. Survival rates for early stage detection is about 5 times that of late stage cancers. For example, patients with a tumor that has not breached the muscularis mucosa (TNM stage T1-2, N0, M0) have an average 5-year survival of approximately 90%. Those with a more invasive tumor, yet without node involvement (T3-4, N0, M0) have an average 5-year survival of approximately 70%. Patients with positive regional lymph nodes (any T, N1-3, M0) have an average 5-year survival of approximately 40%, while those with distant metastases (any T, any N, M1) have an average 5-year survival of approximately 5%.

CEA level is also directly related to the prognosis of disease, since its level correlates with the bulk of tumor tissue.

Follow Up:
The aims of follow-up are to diagnose, in the earliest possible stage, any metastasis or tumors that develop later, but did not originate from the original cancer (metachronous lesions).

The U.S. National Comprehensive Cancer Network and American Society of Clinical Oncology provide guidelines for the follow-up of colon cancer.[93][94] A medical history and physical examination are recommended every 3 to 6 months for 2 years, then every 6 months for 5 years. Carcinoembryonic antigen blood level measurements follow the same timing, but are only advised for patients with T2 or greater lesions who are candidates for intervention. A CT-scan of the chest, abdomen and pelvis can be considered annually for the first 3 years for patients who are at high risk of recurrence (for example, patients who had poorly differentiated tumors or venous or lymphatic invasion) and are candidates for curative surgery (with the aim to cure). A colonoscopy can be done after 1 year, except if it could not be done during the initial staging because of an obstructing mass, in which case it should be performed after 3 to 6 months. If a villous polyp, a polyp >1 centimeter or high grade dysplasia is found, it can be repeated after 3 years, then every 5 years. For other abnormalities, the colonoscopy can be repeated after 1 year.

Routine PET or ultrasound scanning, chest X-rays, complete blood count or liver function tests are not recommended. These guidelines are based on recent meta-analyses showing intensive surveillance and close follow-up can reduce the 5-year mortality rate from 37% to 30%.

Prevention:
People are encouraged to eat plenty of fresh fruit and vegetables, as this appears to reduce the risk. A high-fibre diet with plenty of fruit, vegetables and carbohydrates (pasta, bread, rice) is believed to reduce the risk of colorectal cancer. Moderate amounts of exercise may also protect against bowel cancer.

Eating a diet high in saturated fat and red meat, and low in fibre, smoking and being overweight, increases your risk as does drinking excessive amounts of alcohol.

Eating at least five portions of fruit and vegetables every day is thought to protect against this and many different cancers through the benefits of the antioxidant vitamins and minerals they contain.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

 

Resources:
http://www.medicinenet.com/colon_cancer/article.htm
http://en.wikipedia.org/wiki/Colorectal_cancer
http://search.myway.com/search/GGmain.jhtml?pg=AJmain&action=click&searchfor=colorectal+cancer&ss=sub&st=site&ct=TG
http://www.bbc.co.uk/health/physical_health/conditions/in_depth/cancer/typescancer_bowel.shtml
http://www.mayoclinic.com/health/colon-cancer/DS00035

http://www.bbc.co.uk/health/physical_health/conditions/in_depth/cancer/typescancer_bowel.shtml

http://www.khg2.net/colon-cancer/

http://www.metrohealth.org/body.cfm?id=1628&oTopID=1616

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