Colorectal carcinoma, or colon cancer, is a deadly disease that affects upwards of 135,000 and kills more than 55,000 patients per year, according to an article in the March 2005 "Clinics in Laboratory Medicine." Protocols such as rectal exams and colonoscopies exist for screening high-risk populations such as the elderly and genetically predisposed. Symptoms are often nonspecific, and it's difficult to make a definitive diagnosis, which requires vigilance on the part of the physician to evaluate for possible colon cancer.
Abdominal Pain
Abdominal discomfort can be felt by patients afflicted by colon cancer. This can be from many reasons, such as invasion of the cancer into local tissues, obstruction of the colon and death of cancer cells from outgrowing their own blood supply.
Rectal Bleeding
This can manifest as blood in the stool or blood on toilet paper after wiping. Often, the blood can be mixed in with stool and hard to visualize without testing that can determine trace amounts of blood in the feces. The blood can also be dark colored (known as melena) as a result of metabolism of the hemoglobin during transit in the colon.
Anemia
The patient can become anemic (from deficiency of iron) from chronic bleeding that can result from colon cancer. Symptoms include skin pallor and fatigue. In addition, the deficiency of iron can result in nail problems (known as koilonychia), swelling and color changes of the tongue, and scaling of the lips.
Obstruction
The tumor can grow into the colon space, obstructing the flow of feces into the rectum and out of the body. Symptoms can include pain, decreased flatulence, constipation, and even vomiting mixed with fecal contents if obstruction becomes severe. The left colon is narrower and thus obstruction is more common in this part of the colon.
Weight Loss
Many cancer syndromes result in wasting and weight loss. This is a result of increased levels of a chemical known as tumor necrosis factor, or cachexin. This increases the body's inflammatory response, and when this continues the body tends to enter a state of malnutrition and loses lean tissue. This sort of weight loss does not respond to nutritional therapy, and treatment of the underlying cancer is necessary to resolve the malnutrition. This is especially prominent when cancers metastasize, or spread to other organs.
Lymph Node Swelling
This is known by the medical term "lymphadenopathy" and is a result of cancer's spread to the lymph nodes. Characteristic nodes are the "Sister Mary Joseph node," which can be felt around the bellybutton, and the "Virchow's node," which is found in the area right above the left clavicle.
Swelling
The patient can also notice swelling of the abdomen and extremities, such as the lower limbs. This is usually a result of extension into the liver (a very common site of spread) and disruption of liver function, which includes synthesizing proteins. As a result of decreased circulating proteins in the bloodstream, the body tends to lose fluid in spaces such as the abdomen and lower limbs.
Change in Bowel Habits
Colon cancer can present with either diarrhea or constipation. While either is possible, recent changes in bowel habits tend to point more toward cancer than other chronic bowel conditions. In addition, the stools can be described as "pencil thin" from squeezing through a partially obstructed colon.
References
- "Clinics in Laboratory Medicine;" From Colonic Polyps to Colon Cancer: Pathophysiology, Clinical Presentation, and Diagnosis; Cappell, M. Volume 25, March 2005.
- "Cecil Medicine, 23rd Edition;" Goldman; 2007
- "Abeloff's Clinical Oncology, 4th Edition;" Abeloff; 2008
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