Colorectal cancer
Colorectal cancer: Excerpt from Handbook of Diseases
In the United States and Europe, colorectal cancer is the second most common visceral neoplasm. Incidence is equally distributed between men and women. Colon cancer affects more than twice as many people as rectal cancer. Incidence increases with age, with most patients older than age 55. Higher incidence occurs in patients with a family history of colorectal cancer and in those who have chronic inflammatory bowel disease or polyps.
Colorectal malignant tumors are almost always adenocarcinomas. About half of these are sessile lesions of the rectosigmoid area; the rest are polypoid lesions.
Colorectal cancer tends to progress slowly and remains localized for a long time. Consequently, it’s potentially curable in 75% of patients if an early diagnosis allows resection before nodal involvement. With early diagnosis, the overall 5-year survival rate is about 50%.
Causes
The exact cause of colorectal cancer is unknown, but studies showing concentration in areas of higher economic development suggest a relation to diet (excess animal fat, particularly beef, and low fiber). Other factors that increase the risk of developing colorectal cancer include:
❑ other diseases of the digestive tract
❑ age (older than 40)
❑ history of ulcerative colitis (the average interval before onset of cancer is 11 to 17 years)
❑ familial polyposis (cancer almost always develops by age 50).
Signs and symptoms
Signs and symptoms of colorectal cancer result from local obstruction and, in later stages, from direct extension to adjacent organs (bladder, prostate, ureters, vagina, sacrum) and distant metastasis (usually to the liver).
In the early stages, signs and symptoms are typically vague and depend on the anatomical location and function of the bowel segment containing the tumor. Later, they generally include pallor, cachexia, ascites, hepatomegaly, and lymphangiectasis.
Cancer on the right side
On the right side of the colon (which absorbs water and electrolytes), early tumor growth causes no signs of obstruction because the tumor tends to grow along the bowel rather than surround the lumen, and the fecal content in this area is normally liquid. It may, however, cause black, tarry stool; anemia; and abdominal aching, pressure, or dull cramps.
As the disease progresses, the patient develops weakness, fatigue, exertional dyspnea, vertigo and, eventually, diarrhea, obstipation, anorexia, weight loss, vomiting, and other signs and symptoms of intestinal obstruction. In addition, a tumor on the right side may be palpable.
Cancer on the left side
On the left side, a tumor causes signs and symptoms of an obstruction even in early stages because in this area, stool is of a formed consistency. It commonly causes rectal bleeding (typically ascribed to hemorrhoids), intermittent abdominal fullness or cramping, and rectal pressure.
As the disease progresses, the patient develops obstipation, diarrhea, or “ribbon” or pencil-shaped stool. Typically, he notices that passage of stool or flatus relieves the pain. At this stage, bleeding from the colon becomes obvious, with dark or bright red blood in the stool and mucus in or on the stool.
Rectal tumor signs
With a rectal tumor, the first indication is a change in bowel habits, often beginning with an urgent need to defecate on arising (“morning diarrhea”) or obstipation alternating with diarrhea. Other indications include blood or mucus in stool and a sense of incomplete evacuation.
Late in the disease, pain begins as a feeling of rectal fullness that later becomes a dull and sometimes constant ache confined to the rectum or sacral region.
Diagnosis
Only a tumor biopsy can verify colorectal cancer, but the following tests help detect it:
❑ Digital examination can help detect almost 15% of colorectal cancers.
❑ Hemoccult test (guaiac) may show blood in the stool.
❑ Proctoscopy or sigmoidoscopy can help detect up to 66% of colorectal cancers.
❑ Colonoscopy permits visual inspection (and photographs) of the colon up to the ileocecal valve and gives access for polypectomies and biopsies of suspected lesions.
❑ Computed tomography scan helps detect areas affected by metastasis.
❑ Barium X-ray, using a dual contrast with air, can locate lesions that are undetectable manually or visually. Barium examination should follow endoscopy or excretory urography because the barium sulfate interferes with these tests.
❑ Carcinoembryonic antigen, although not specific or sensitive enough for an early diagnosis, is helpful in monitoring patients before and after treatment to detect metastasis or recurrence.
Treatment
The most effective treatment for colorectal cancer is surgery to remove the malignant tumor and adjacent tissues as well as any lymph nodes that may contain cancer cells. The type of surgery depends on the location of the tumor:
❑ Cecum and ascending colon: A right hemicolectomy (for advanced disease) is performed. It may include resection of the terminal segment of the ileum, cecum, ascending colon, and the right half of the transverse colon with corresponding mesentery.
❑ Proximal and middle transverse colon: A right colectomy is performed 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 is typically limited to the sigmoid colon and mesentery.
❑ Upper rectum: Anterior or low anterior resection is performed. A newer method, using a stapler, allows for resections much lower than were previously possible.
❑ Lower rectum: Abdominoperineal resection and permanent sigmoid colostomy is performed.
Chemotherapy is indicated for patients with metastasis, residual disease, or a recurrent inoperable tumor. Drugs used in such treatment commonly include fluorouracil with levamisole, leucovorin, methotrexate, or streptozocin. Patients whose tumor has extended to regional lymph nodes may receive fluorouracil and levamisole for 1 year postoperatively.
Radiation therapy induces tumor regression and may be used before or after surgery or combined with chemotherapy, especially fluorouracil.
Special considerations
Before surgery:
❑ Monitor the patient’s diet modifications, laxatives, enemas, and antibiotics — all are used to clean the bowel and to decrease abdominal and perineal cavity contamination during surgery.
❑ If the patient is having a colostomy, teach him and his family about the procedure.
❑ Inform the patient that the stoma will be red, moist, and swollen and that postoperative swelling will eventually subside.
❑ Show the patient a diagram of the intestine before and after surgery, stressing how much of the bowel will remain intact. Supplement your teaching with instructional aids. Arrange a postsurgical visit from a recovered ostomate.
❑ Prepare the patient for postoperative I.V. infusions, a nasogastric tube, and an indwelling urinary catheter.
❑ Discuss the importance of cooperating during deep-breathing and coughing exercises.
After surgery:
❑ Explain to the patient’s family the importance of their positive reactions to the patient’s adjustment. Consult with an enterostomal therapist, if available, to help set up a regimen for the patient.
❑ Encourage the patient to look at the stoma and participate in its care as soon as possible. Teach good hygiene and skin care. Allow him to shower or bathe as soon as the incision heals.
❑ If appropriate, instruct the patient with a sigmoid colostomy to do his own irrigation as soon as he can after surgery. Advise him to schedule irrigation for the time of day when he normally evacuated before surgery. Many patients find that irrigating every 1 to 3 days is necessary for regularity.
❑ If flatus, diarrhea, or constipation occurs, eliminate suspected causative foods from the patient’s diet. He may reintroduce them later.
❑ After several months, many ostomates establish control with irrigation and no longer need to wear a pouch. A stoma cap or gauze sponge placed over the stoma protects it and absorbs mucoid secretions.
❑ Before achieving such control, the patient can resume physical activities, including sports, but he should avoid injury to the stoma or surrounding abdominal muscles.
❑ Inform the patient that a structured, gradually progressive exercise program to strengthen abdominal muscles may be instituted under medical supervision.
❑ Instruct the patient to avoid heavy lifting because herniation or prolapse may occur through weakened muscles in the abdominal wall.
❑ Encourage the patient to discuss feelings about sexuality and functioning. If appropriate, refer the patient to a home health agency for follow-up care and counseling. Suggest sexual counseling for male patients; most are impotent after an abdominoperineal resection.
Clinical tip Anyone who has had colorectal cancer is at increased risk for another primary cancer. Instruct the patient to have yearly screening and testing and to maintain a high-fiber diet.
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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- "Signs & Symptoms: A 2-in-1 Reference for Nurses" (2007)
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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» Next page: Rectal pain (Signs & Symptoms: A 2-in-1 Reference for Nurses)
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