Colorectal Cancer

COLORECTAL CANCER – Causes, Stages, Pathophysiology, Signs and Symptoms, Diagnostic Tests and Medical Management

DEFINITION

Colorectal cancer, commonly known as colon cancer or bowel cancer, is a cancer from uncontrolled cell growth in the colon or rectum (parts of the large intestine), or in the appendix. Colorectal cancer refers to the malignancies of colon and rectum.

CAUSE

• High intake of fat
• Alcohol
• Red meat
• Obesity
• Smoking
• Lack of physical exercise
• Older age
• Male gender
• Family history of colorectal cancer and polyps
• Presence of polyps in the large intestine
• Inflammation bowel diseases
• Chronic ulcerative colitis

STAGES OF COLORECTAL CANCER

Colon and rectal cancer are staged according to how far they have spread through the walls of the colon and rectum and whether they have spread to other parts of the body.

Staging Colon Cancer

Stage O: Stage O cancer of the colon is very early cancer. The cancer is found only in the innermost lining of the colon.

Stage I: the cancer has spread beyond the innermost lining of the colon to the second and third layers and involves the inside wall of the colon. The cancer has not spread to the outer wall of the colon or outside the colon.

Stage II: the tumor extends through the muscular wall of the colon, but there is no cancer in the lymph nodes (small structures that are found throughout the body that produce and store cells that fight infection

Stage III: the cancer has spread outside the colon to one or more lymph nodes (small structures that are found throughout the body that produce and store cells that fight infection)

Stage IV: the cancer has spread outside the colon to other parts of the body, such as the liver or the lungs. The tumor can be any size and may or may not include affected lymph nodes.

Staging Rectal Cancer

Rectal cancer is staged much the same way as colon cancer, but because the tumor is much lower down in the colon, the treatment options may vary.

Stage O: in stage O rectal cancer, the tumor is located only on the inner lining of the rectum. To treat this early stage cancer, surgery can be performed to remove the tumor or a small section of the rectum where the cancer can be removed.

Stage I: this is an early form or limited form of cancer. The tumor has broken through the inner lining of the rectum but has not made it past the muscular wall

Stage II: this cancer is a little more advanced. The tumor has penetrated all the way through the bowel wall and may have invaded other organs, such as the bladder, uterus, or prostate gland

Stage III: the tumor has spread to the lymph nodes (small structures that are found throughout the body that produce and store cells that fight infection)

Stage IV: the tumor has spread to distant parts of the body (metastasized). The tumor can be any size and sometimes is not that large. The liver and lung are two favored places for rectal cancer to spread.

PATHOPHYSIOLOGY

Cancers of the colon and rectum (colorectal cancer) start when the process of the normal replacement of lining cells goes away —- mistakes in mucosal cell division occur frequently —- these cells begin to divide independently of the normal checks and balances that control growth —- lead to growths within the colon called polyps —- polyps are precancerous tumors that grow slowly over the course of years and do not spread — as polyps grow, additional genetic mutations further destabilize the cells —- make the cells more bizarre and invade other layers of the large intestine (such as the submucosa or muscular layer), the precancerous polyp has become cancerous (within at least 8 to 10 years) —- once a colorectal cancer forms, it begins to grow in two days.

First Way — first, the cancer can grow locally and extend through the wall of the intestine —- invade adjacent structures, making the mass (called the primary tumor) more of a problem and harder to remove — cause pain or fullness, or cause blockages of the colon or nearby structures.

Second Way — second, as the cancer grows it begins the process of metastasis, shedding thousands of cells a day into the blood and lymphatic system — spread first to local lymph nodes —- spread to the liver, the abdominal cavity, and the lung are the next most common destinations of metastatic spread.

SIGNS AND SYMPTOMS

The symptoms and signs of colorectal cancer depend on the location of tumor in the bowel, and whether it has spread elsewhere in the body (metastasis). The classic warning signs include:

• Worsening constipation
• Blood in the stool
• Weight loss, fever
• Loss of appetite
• Nausea and vomiting in someone over 50 years old
• Rectal bleeding
• Anemia
• Weight loss
• Change in bowel habits

DIAGNOSTIC TESTS

• Stool test for colon cancer: finding colon cancer early is key to beating it. That is why doctors recommend a yearly fecal occult blood test, which tests for invisible blood in the stool, an early signs of colon cancer.
• Fecal occult blood test: fecal occult blood is tested for the presence of microscopic or invisible blood in the stool, such as a growth, or polyp, or cancer in the colon or rectum. If microscopic blood is detected, it is important for doctor to determine the source of bleeding to properly diagnose and treat the problem.

Reason for blood to appear in Stool

Blood may appear in the stool because of one or more of the following conditions:

• Benign (noncancerous) or malignant (cancerous) growths or polyps of the colon
• Hemorrhoids (swollen blood vessels near the anus and lower rectum that can rupture causing bleeding)
• Anal fissures (splits or cracks in the lining of the anal opening)
• Intestinal infections that cause inflammation
• Ulcers
• Ulcerative colitis
• Crohn’s disease
• Diverticular disease, caused by outpouchings of the colon wall
• Abnormalities of the blood vessels in the large intestine
• Colonoscopy for colon cancer: one of the best tools for detecting colon cancer is a colonoscopy. Colonoscopy is an outpatient procedure during which large bowel (colon and bowel) is examined from the inside. Colonoscopies are usually used to evaluate symptoms like abdominal pain, rectal bleeding, or changes in bowel habits. They are also used to screen for colorectal cancer.

Colonoscopy

The procedure is performed by a doctor experienced in colonoscopy and lasts approximately 30 to 60 minutes. Medications will be given into vein to make patient feel relaxed and drowsy. Patient will be asked to lie on his/her left side on the examining table. During a colonoscopy, the doctor uses a colonoscope, a long, flexible, tubular instrument about 1/2 inch in diameter that transmits an image of the lining of the colon so the doctor can examine it for any abnormalities. The colonoscope is inserted through the rectum and advanced to the other end of the large intestine.

The scope bends, so the doctor can move it around the curves of his/her colon. Patient may be asked to change position occasionally to help the doctor move the scope. The scope also blows air into the colon, which expands the colon and helps to visualize better.

Patient may feel mild cramping during the procedure. Patient can reduce the cramping by taking several slow, deep breaths during the procedure. When the doctor has finished, the colonoscope is slowly withdrawn while the lining of bowel is carefully examined.

• Sigmoidoscopy for colorectal cancer screening: sigmoidoscopy enables the physician to look at the inside of the large intestine from the rectum through the last part of the colon, called the sigmoid colon
• CT scan and MRI for colon cancer
• Genetic testing for colon cancer

MEDICAL MANAGEMENT

Chemotherapy

Chemotherapy uses drugs to destroy cancer cells. Chemotherapy can be used to destroy cancer cells after surgery, to control tumor growth or to relieve symptoms of colon cancer.

Radiation Therapy

Radiation Therapy uses powerful energy sources, such as X-rays, to kill any cancer cells that might remain after surgery, to shrink large tumors before an operation so that they can be removed more easily, or to relieve symptoms of colon cancer and rectal cancer. Radiation therapy is rarely used in early-stage colon cancer, but is a routine part of treating rectal cancer, especially if the cancer has penetrated through the wall of the rectum or travelled to nearby lymph nodes. Radiation therapy, usually combined with chemotherapy, may be used after surgery to reduce the risk that the cancer may recur in the area of the reaction where it began.

Targeted Drug Therapy

Drugs that target specific defects that allow cancer cells to proliferate are available to people with advanced colon cancer, including bevacizumab (avastin), cetuximab (erbitux) and panitumumab (vectibix). Targeted drugs can be given along with chemotherapy or alone. Targeted drugs are typically reserved for people with advanced colon cancer.

Alternative Treatment

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 diagnosis might include sadness, anger, difficulty concentrating, difficulty sleeping and loss of appetite. Alternative treatments may help redirect thoughts away from your fears, at least temporarily, to give some relief.

Alternative treatments that may help relieve distress include:

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