Colorectal Cancer

Colorectal Cancer:  This disorder ranks the second most common visceral cancer in the United States and in Europe, affecting men and women equally.

Colorectal malignant tumors  are almost always adenocarcinomas (carcinoma derived from glandular tissue or in which the tumor cells form recognizable glandular structures).  About  half of these are sessile (attached by a broad base, as opposed to being pedunculated or stalked) lesions of the rectosigmoid area; the rest are polypoid (resembling a polyp) lesions.  This type of cancer  usually spreads slowly, it's potentially curable in  most patients if early diagnosis allows resection before nodal involvement.  With improved diagnosis, the overall 5 yea survival rate is estimated at 55%.

Cause:  The exact cause of colorectal cancer is unknown.  Studies show concentration in areas of higher economic development, suggesting a connection to a high fat diet.  High risk factors include other diseases of the digestive tract; age over 40; history of ulcerative colitis (average interval before onset of cancer is 11 to 17 years); and familial polyposis (cancer usually almost develops by age 50).

Symptoms:

Signs and symptoms of colorectal cancer result from local obstruction and, in later stages, from direct extension to adjacent organs (such as; bladder, prostate, uterus, vagina, sacrum) and distant metastasis (usually to the liver). 

Later;  Pallor, cachexia (general ill health and malnutrition), ascites (effusion and accumulation of serous fluid in the abdominal cavity). hepatomegaly (enlargement of the liver), or lymphangiectasis (dilation of the lymphatic vessels).

On the right side of the colon (which absorbs water and electrolytes), early tumor growth causes no obstruction, because the tumor tends to grow along the bowel rather than the surrounding lumen, and the fecal content in this area is usually liquid.  It may cause black tarry stools; anemia, and abdominal aching, pressure, or dull cramps. 

As the disease progress:  Patient may develop -weakness, fatigue, exertional dyspnea (difficulty breathing), vertigo, diarrhea, obstipation( intractable constipation), anorexia, weight loss, vomiting, and other signs of intestinalobstruction. By this time tumor on the right side may be palpable.

On the left side of the colon:  ( where stools are denser, a tumor is obstructive even in early stages).  Symptoms  usually will have rectal bleeding , intermittent abdominal fullness or cramping, and rectal pressure. 

As the disease progress:  Patients may develop - obstipation, diarrhea, or "ribbon" or pencil - shaped stools.  Usually the patient notices that passage of a stool or flatus relieves the pain.  At this stage bleeding from the colon becomes obvious, with blood or mucus in stools.

A rectal tumor is noted by a change in bowel habits, often beginning with an urgent need to defecate on arising (or morning diarrhea) or obstipation alternating with diarrhea.  Other signs are blood or mucus in the stool and a 'feeling of ' incomplete evacuation. 

Later stage:  Pain begins as a feeling of rectal fullness that later becomes a dull, and sometimes constant, ache confined to the rectum or sacral region.

Treatment:

Surgical treatment to remove the malignant tumor and adjacent tissues, as well as any lymph nodes that may contain cancer cells.  -Type of surgery depends on the location and type of tumor.

For cecum and ascending colon:  Right hemicolectomy for advanced disease may include resection of the terminal segment of the ileum, cecum, ascending colon, and right half of the transverse colon with corresponding mesentery.

For proximal and middle transverse colon:  Right colectomy includes - transverse colon and mesentery corresponding to midcolonic vessels, or the surgeon may perform segmental resection of the transverse colon and associated midcolonic vessels.

For sigmoid colon tumors:  Surgery is usually limited to the sigmoid colon and mesentery.

Upper rectum tumors:  usually call for anterior or low anterior resection.  A newer procedure, using a stapler, allows for resections much lower than were previously possible.

Lower rectum tumors:  Usually abdominoperineal resection and permanent sigmoid colostomy.

Chemotherapy is indicated for patients with metastasis, residual disease, or a recurrent inoperable tumor.

Drug therapy

Radiation Therapy - may be use before or after surgery

Biotherapy - is still experimental 

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