Colon Cancer

COLORECTAL CANCER

The colon is the final part of the digestive tract. Colon cancer is a type of cancer that begins in the colon (large intestine).

Though it can happen at any age, this cancer typically affects older adults. It usually begins as small, noncancerous clumps of cells that form on the inside of the colon. Over time some of these clumps (also called polyps) can become colon cancers.

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

Many treatments are available to help control colon cancer if it develops, including surgery, radiation therapy and drug treatments such as chemotherapy, targeted therapy and immunotherapy.

This type of cancer is sometimes called colorectal cancer, which is actually a term that combines colon cancer and rectal cancer, which begins in the rectum.

WHAT IS COLORECTAL CANCER?

Colorectal cancer is a cancer that starts either in the rectum or colon. Both of these organs are in the lower portion of the digestive system. The colon is also known as the large intestine. The rectum is at the end of the colon.

The doctor may use staging as a guideline to determine how far the cancer has gone. It is important for the doctor to know the stage of the cancer so as to be able to come up with the best treatment plan as well as give an estimate of the long-term outlook.

Stage 1 is the earliest stage. The stages progress up to stage 4, which is the most advanced stage. Below are the stages of colorectal cancer:

Stage 1. - The cancer has penetrated the lining, or mucosa, of the colon or rectum but is yet to spread to the organ walls.

Stage 2. - The cancer has spread to the walls of the colon or rectum but has not yet affected the lymph nodes or nearby tissues.

Stage 3. - The cancer has moved to the lymph nodes but not to other parts of the body yet. Usually at this stage, one to three lymph nodes are involved.

Stage 4. - The cancer has spread to other distant organs, such as the liver or lungs.

TYPES OF COLORECTAL CANCER

There are many types of colorectal cancer. Most common among them is Adenocarcinoma. The other types include colorectal lymphoma, carcinoid tumors and gastrointestinal stromal tumors.

Hereditary colorectal cancers, (which means that several generations of a particular family have had colorectal cancer) include familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC).

Below is an overview of some of the types of cancer in the colon and rectum;

• Adenocarcinoma - Adenocarcinomas are tumors that start in the lining of internal organs. The term 'Adeno' means gland. These are tumors that begins in cells with glandular properties, or cells that secrete. They can form in many other organs, such as the lung or the breast. In colorectal cancer, early tumors begins as small adenomatous polyps that continue to grow and then turn into malignant tumors. Most of colorectal cancers are adenocarcinomas.
• Gastrointestinal Stromal Tumors (GIST) - These tumors begin in the muscle tissue of the digestive tract, although they rarely appear in the colon. They can be noncancerous (benign) initially, but most often turn into cancer. When this happens, they are called sarcomas. The usual treatment is surgery if the tumor is yet to spread.
• Lymphoma – Typically, this is a cancer that starts in a lymph node, which is part of the immune system. However, it can also start in the colon or rectum.
• Carcinoids - Often causing no symptoms, carcinoids are tumors that start in special hormone-producing cells in the intestine. The usual treatment is surgery.
• Turcot Syndrome - This syndrome is a rare disorder that includes colorectal polyposis, colon cancer, and brain tumors.
• Peutz-Jeghers Syndrome (PJS) - Peutz-Jeghers syndrome is an autosomal dominant disorder that is associated with the following characteristics:
• Melanocytic macules (dark blue or brown moles) - These moles can be located around and/or in the mouth including the lips, and around the eyes, nostrils, and anus. Sometimes the dark moles may also appear on the fingers.
• Multiple polyps in the gastrointestinal tract
• Increased risk of noncancerous (benign) tumors of the ovaries and testes.
• Increased risk of cancers of the esophagus, colon, stomach, breast, and pancreas.
• Familial Colorectal Cancer (FCC) – A lot of colorectal cancer patients have family members with colorectal cancer, but do not have a known colorectal cancer syndrome such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colon cancer (HNPCC). Genes may be identified to explain these family histories.
• Juvenile Polyposis Coli - This is a rare, childhood-onset disease. It is an autosomal dominant disorder that results from mutations in various cancer susceptibility genes, including the SMAD4/DPC4 and BMPR1A genes. The condition is associated with growth that is made up of abnormal mixture of cells and tissues (hamartomatous polyps).

Symptoms can include:

Diarrhea

Hemorrhage

Protein-losing enteropathy

CAUSES OF COLORECTAL CANCER

The causes of most colon cancers have not yet been established.

Colon cancer begins generally when healthy cells in the colon develop mutations (changes) in their DNA. The DNA of a cell contains a set of instructions that tell a cell what to do.

Within the normal scheme of things, healthy cells grow and divide in an orderly way to keep the body functioning normally. However, when a cell's DNA is damaged and becomes cancerous, cells continue to divide even at times when new cells are not needed. As the cells accumulate, they form a tumor.

With the passage of time, cancer cells can grow, invade and destroy normal tissue close by. Cancerous cells can also travel to other parts of the body to form deposits (metastasis).

RISK FACTORS

Some factors that may increase one's risk of colon cancer include:

• A personal history of polyps or colorectal cancer - An individual who has ever had colon cancer or noncancerous colon polyps, has a greater risk of colon cancer in the future.
• Inflammatory intestinal conditions - Some inflammatory diseases of the colon, such as ulcerative colitis and Crohn's disease, can increase the risk of colon cancer.
• A sedentary lifestyle - Inactive people are more likely to develop colon cancer. Getting into regular physical activity may reduce the risk of colon cancer.
• Older age – Although colon cancer can be diagnosed at any age, most of the people with the cancer are older than 50 years. It has been noted however, that for reasons yet to be explained, the rates of colon cancer in people younger than 50 has been on the rise.
• African-American people – Some studies have identified African-Americans as having a greater risk of colon cancer than people of other races.
• Inherited syndromes - Some gene mutations passed through generations of a family can increase the risk of colon cancer significantly. The most common inherited syndromes that increase colon cancer risk are Lynch syndrome, which is also known as hereditary non-polyposis colorectal cancer (HNPCC) and familial adenomatous polyposis (FAP.
• Family history of colon cancer – one is more likely to develop colon cancer if he/she has a blood relative who has had the disease. The risk is even greater if more than one family member has a history of colon or rectal cancer.
• Low-fiber-high-fat diet – a typical Western diet is low in fiber and high in fat and calories. Colon and rectal cancer may be associated with this diet even though studies has had mixed results. Some other studies found an increased risk of colon cancer in people who eat foods high in red and processed meat.

Diabetes – Diabetes patients or people with insulin resistance have an increased risk of colon cancer.

Obesity - Obese people have an increased risk of colon cancer and an increased risk of even dying of colon cancer if compared with people considered normal in weight.

Smoking - Smokers may have an increased risk of colon cancer.

Alcohol - Heavy use of alcohol increases the risk of colon cancer.

Radiation therapy for cancer - Radiation therapy which is directed at the abdomen to treat previous cancers increases the risk of colon cancer.

SYMPTOMS OF COLORECTAL CANCER

Often times, colorectal cancer may not present any symptoms, especially in the early stages. If patients experience any symptoms at all during the early stages, they may include:

• Abdominal pain
• Excessive gas
• Bleeding from the rectum
• Diarrhea
• Abdominal cramps
• Constipation
• Changes in stool color
• Changes in stool shape (e.g. narrowed stool)
• Blood in stool

Stage 3 or 4 symptoms (late stage symptoms)

Symptoms of Colorectal cancer are more noticeable in the stages 3 and 4 (late stages). In addition to the symptoms above, one might also experience the following;

• Excessive fatigue
• Unintentional weight loss
• Changes in stool that may last longer than a month
• Unexplained weakness
• Constant feeling like bowels did not empty completely
• Vomiting

Should the colon cancer spreads to other parts of the body, one may also experience:

• Blurry vision
• Swelling in hands or feet
• Breathing difficulties
• Jaundice (yellow eyes and skin)
• Chronic headaches
• Bone fractures

WHEN TO SEE A DOCTOR

People should make appointment with their doctor if they notice any persistent symptoms that are of worry.

The guidelines generally recommend that colon cancer screenings begin around age 50. The doctor may recommend more frequent or earlier screening if there are other risk factors, such as a family history of the disease.

DIAGNOSIS

An early diagnosis of colorectal cancer provides the best chance of a cure.

The doctor will begin by extracting information from patient about medical and family history. This may be followed by the performance of a physical exam. The patient's abdomen may be pressed or a rectal exam be conducted to determine the presence of lumps or polyps.

• Blood testing - Some blood tests may be conducted to get a better idea of what could be causing the symptoms. There is actually no blood test that specifically checks for colorectal cancer, however, liver function tests and complete blood count tests can rule out the presence of other diseases and disorders.
• Colonoscopy - This involves the use of a long tube with a small camera attached. It allows the doctor to see the inside of the colon and rectum to check for anything unusual. The doctor can also remove tissue from abnormal areas during a colonoscopy.
• X-ray - An X-ray using a radioactive contrast solution that contains the metallic element barium may be ordered by the doctor. This liquid will be inserted into the bowels through the use of an enema. The barium solution goes to coat the lining of the colon, which helps improve the quality of the X-ray images.
• CT scan - This scan provides the doctor with a detailed image of the colon. When it is used in diagnosing colorectal cancer, another name for a CT scan is a virtual colonoscopy.

TREATMENT

Treatment of colorectal cancer depends on a variety of factors. The state of the patient's overall health and the stage of the colorectal cancer will aid the doctor in creating a treatment plan.

• Surgery - It might be possible for the surgeon to remove cancerous polyps through surgery in the earliest stages of colorectal cancer. It will be most likely to have an excellent outlook if the polyp has not attached to the wall of the bowels. If the cancer has already spread into the bowel walls, the surgeon may need to remove a portion of the colon or rectum and possibly along with any neighboring lymph nodes. If possible, the surgeon will reattach the remaining healthy portion of the colon to the rectum. Otherwise, a colostomy may be performed to create an opening in the abdominal wall for the removal of waste. The colostomy may be temporary or permanent.
• Chemotherapy - Chemotherapy makes use of drugs to kill cancer cells. In the case of colorectal cancer, chemotherapy is a common treatment that is used after surgery to destroy any remaining cancerous cells. Chemotherapy also controls the growth of tumors. Even though chemotherapy provides some relief from symptoms in late-stage cancer, it often comes with side effects that need to be controlled with additional medication.
• Radiation - Radiation uses a powerful beam of energy (close to what is used in X-rays), to target and destroy cancerous cells before and after surgery. Radiation therapy is commonly used alongside chemotherapy.

PREVENTION

Avoiding the risk factors could prevent or at least reduce the level of risk of this condition. The following risk factors increase the risk of colorectal cancer:

Age - The risk of colorectal cancer increases after age 50. Most cases of colorectal cancer are diagnosed after age 50.

Family history – If one has a parent, brother, sister, or child with colorectal cancer, it doubles his/her risk of colorectal cancer.

Inherited risk - The risk of colorectal cancer is enhanced when certain gene changes that are linked to familial adenomatous polyposis (FAP) or hereditary non-polyposis colon cancer (HNPCC or Lynch Syndrome) are inherited.

Alcohol - Drinking alcohol is also linked to the risk of forming large colorectal adenomas. 3 or more alcoholic beverages per day increases the risk of colorectal cancer. (benign tumors).

Cigarette smoking – The smoking of cigarettes increases the risk of having colorectal cancer and death from same. Cigarette smoking is also linked to an increased risk of forming colorectal adenomas. A cigarette smoker who has had surgery to remove colorectal adenomas is at an increased risk for the return of the adenomas.

Race - African Americans automatically have an increased risk of colorectal cancer if compared to people of other races.

Obesity - Obesity has been linked to an increased risk and death from colorectal cancer.

Personal history – A personal history of the following conditions increases the risk of colorectal cancer:

• Previous colorectal cancer - High-risk adenomas (colorectal polyps that are large or that have cells that look abnormal).
• Ovarian cancer - Inflammatory bowel disease (e.g. ulcerative colitis or Crohn disease)

The following protective factors can also decrease the risk of colorectal cancer:

• Physical activity - A lifestyle that includes regular physical activity reduces the risk of colorectal cancer.
• Aspirin - Studies have shown that taking aspirin lowers the risk of colorectal cancer and the risk of death from colorectal cancer. The possible harms of aspirin use (100 mg or less) daily or every other day include an increased risk of bleeding in the stomach and intestines. These risks may generally be greater among the elderly, men, and those with conditions that have a high risk of bleeding.
• Combination hormone replacement therapy – Studies reveal that combination hormone replacement therapy (HRT) that includes both estrogen and progestin lowers the risk of invasive colorectal cancer in postmenopausal women. However, in women who take combination HRT but still develop colorectal cancer, the cancer is more likely to be advanced when it is diagnosed. The possible harms of combination HRT include an increased risk of having:
• Blood clots.
• Polyp removal
• Breast cancer.
• Heart disease.

Most colorectal polyps are adenomas that may develop into cancer. Therefore, removing large colorectal polyps may lower the risk of colorectal cancer. It has not been established if removing smaller polyps lowers the risk of colorectal cancer.

The possible harms of polyp removal during colonoscopy or sigmoidoscopy include tears in the wall of the colon and bleeding.