Colorectal Cancer - Symptoms & Treatment

Colorectal cancer is malignant cells found in the colon or rectum. The colon and the rectum are part of the large intestine, which is part of the digestive system. Because colon cancer and rectal cancers have many features in common, they are sometimes referred to together as colorectal cancer. Cancerous tumors found in the colon or rectum also may spread to other parts of the body.

Incidence of colorectal cancer is highest in developed countries such as the United States and Japan, and lowest in developing countries in Africa and Asia. Colorectal cancer is the second most common visceral neoplasm in the United States and Europe. It's equally distributed between men and women.

Malignant tumors of the colon or rectum are almost always adenocarcinomas. About half of these are sessile lesions of the rectosigmoid area; the rest are polypoid lesions.

Causes

Although the exact cause of colorectal cancer is unknown, studies show a greater incidence in areas of higher economic development, suggesting a relationship to a diet that includes excess animal fat, especially from beef, and low fiber.

Other factors that magnify the risk of developing colorectal cancer include diseases of the digestive tract, a history of ulcerative colitis (cancer usually starts in 11 to 17 years), and familial polyposis (cancer almost always develops by age 50).

Signs and Symptoms

The following are the most common symptoms of colorectal cancer. However, each individual may experience symptoms differently.

People who have any of the following symptoms should check with their physicians, especially if they are over 50 years old or have a personal or family history of the disease:

• a change in bowel habits such as diarrhea, constipation, or narrowing of the stool that lasts for more than a few days
• rectal bleeding or blood in the stool
• cramping or gnawing stomach pain
• decreased appetite
• vomiting
• weakness and fatigue
• jaundice - yellowing of the skin and eyes

The symptoms of colorectal cancer may resemble other conditions, such as infections, hemorrhoids, and inflammatory bowel disease. It is also possible to have colon cancer and not have any symptoms. Always consult your physician for a diagnosis.

Diagnostic tests 

Colorectal cancer screening and diagnosis may involve one or more of a number of procedures:

• Digital rectal exam
• Fecal occult (hidden) blood test
• Flexible sigmoidoscopy
• Total colonoscopy
• Barium enema
• Genetic testing
• Virtual Colonoscopy

Treatment

The most effective treatment for colorectal cancer is surgery to remove the malignant tumor and adjacent tissues, along with any lymph nodes that may contain cancer cells. After surgery, treatment continues with chemotherapy, radiation therapy, or both.

The type of surgery depends on tumor location:

• Cecum and ascending colon. Tumors in these areas call for right hemicolectomy (for advanced disease). Surgery may include resection of the terminal segment of the ileum, cecum, ascending colon, and right half of the transverse colon with corresponding mesentery.
• Proximal and middle transverse colon. Surgery consists of right colectomy that includes the transverse colon and mesentery corresponding to midcolic vessels, or segmental resection of the transverse colon and associated midcolic vessels.
• Sigmoid colon. Surgery usually is limited to the sigmoid colon and mesentery.
• Upper rectum. A tumor in this area usually requires anterior or low anterior resection. A newer method, using a stapler, allows for much lower resections than previously possible.
• Lower rectum. Abdominoperineal resection and permanent sigmoid colostomy are required.

If metastasis has occurred, or if the patient has residual disease or a recurrent inoperable tumor, he needs chemotherapy. Drugs used in such treatment commonly include fluorouracil combined with levamisole or leucovorin. Researchers are evaluating the effectiveness of fluorouracil with recombinant interferon alfa-2a.

Radiation therapy, used before or after surgery, induces tumor regression.

Prevention

Recent research suggests that a high fiber, low-fat diet plays a role in prevention; how great a role it plays is unclear. Fiber helps to move waste through the colon and may even protect cells in the lining of the colon from developing into polyps. A good rule of thumb is that the average adult should consume at least 25 - 35 grams of fiber daily. This amount can be obtained by eating five half-cup servings of fruits and vegetables every day. For adults, adding a soluble fiber supplement is an easy and practical way to obtain the recommended daily intake of fiber.

Staying active and drinking at least 8 eight-ounce glasses of non-caffeinated fluid daily also is good for digestive health.

By following the recommended screening methods, many polyps and growths can be detected early. Finding and removing colorectal polyps with sigmoidoscopy and colonoscopy clearly reduces the risk of their development into cancers.