Disease Information

Solid Tumor: Colorectal Carcinoma

Alternate Names: Colon cancer, colon carcinoma, adenocarcinoma of the colon

Definition

• Colorectal carcinoma can occur anywhere in the colon or rectum. Together, the colon and rectum form a long, muscular tube called the large intestine (also called the large bowel). The colon makes up the majority of the large intestine; the rectum makes up the last few inches.
• In children and adolescents, these tumors may occur at any site in the large intestine and may or may not be associated with a family history of large bowel cancer.
• The median age of diagnosis for the pediatric form of the disease is 15 years. In the United States, the largest number of cases has been reported from the Mississippi Valley.
• Young patients with long-standing ulcerative colitis are at increased risk; this risk increases with the severity of the colitis.
• African-Americans have an increasing occurrence of colorectal cancer.

Incidence

• Colorectal carcinoma is the third most frequent cancer in adult men and the second most common in adult women; about 150,000 cases are diagnosed in the United States annually.
• It is very rare in children, with fewer than 100 cases occurring annually in patients younger than 20 years of age. The incidence of this tumor is about one of 1 million in this age group.

Influencing Factors

• Familial intestinal polyposis or adenomatous polyposis coli (APC; inherited as a dominant trait) can lead to multiple adenomatous polyps, which may become malignant.
• Early diagnosis of APC and surgical removal of the colon eliminates the risk of developing carcinoma of the large bowel.
• The familial APC syndrome is caused by mutation of a gene on chromosome 5, which normally suppresses the growth of cells lining the intestine.
• Another tumor suppressor gene, on chromosome 18, is associated with progression of polyps to a malignant form.
• Multiple colon carcinomas have also been associated with neurofibromatosis type 1 (NF-l).
• Children with ulcerative colitis are at increased risk of developing colorectal carcinoma.
• There is no evidence that patients younger than 20 with a family history of colorectal carcinoma or belonging to families with hereditary colorectal carcinoma have a greater risk of developing cancer before the age of 20.

Clinical Features and Symptoms

• Symptoms usually include changes in bowel habits (constipation, diarrhea, bloating, pain with bowel movements), an abdominal mass, weight loss, decreased appetite and blood in the stool.
• Any tumor that causes complete obstruction of the large bowel can cause bowel perforation and spread of the tumor cells within the abdominal cavity.
• Colorectal carcinoma is rarely suspected in pediatric patients.
• If the tumor is suspected the stool should be checked for blood, a blood test to measure the levels of carcinoembryonic antigen (CEA) should be done and various medical imaging studies. A direct examination of the large bowel by a fiber optic instrument, known as a colonoscope, should be done. Other radiographic tests that are sometimes done include a barium enema, which highlights features of the colon, a CT scan or MRI of the abdomen. Patients are also examined for metastasis using CT scans of the chest and bone scans.

Treatment Strategies

• Complete surgical removal of the involved part of large intestine is the best option, but in many instances this is impossible because it may be in advanced stages.
• Chemotherapy and radiation therapy are other treatment choices and they are used, depending on location of the tumor and how far it has spread (stage). Chemotherapy  drugs that are commonly used include 5-fluorouracil, leucovorin, irinotecan, oxaliplatin, bevacizumab, and cetuximab..

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