Colon and rectal cancers
Description
An in-depth report on the causes, diagnosis, treatment, and prevention of colorectal cancer.
Alternative Names
Colorectal cancer
Surgery
Surgical removal of the tumor ("resection") along with any affected surrounding tissue is the standard initial treatment for potentially curable colorectal cancers (cancers that have not spread beyond the colon or lymph nodes). Drug therapy, radiation, or both are often used for advanced cancers and are continuously being tested with surgery in different combinations and sequences.
Although choosing a qualified surgeon is critical, choosing a hospital experienced in procedures is also important. The more often colon cancer surgery is performed at a given hospital, the lower the mortality rate at that hospital is likely to be. In one 2000 study, the 30-day postoperative mortality rate for patients treated at hospitals in the top quartile of procedure volume was 3.5%. For hospitals in the bottom quartile, mortality was 5.5%. However, the differences were small, and significantly less than for more complex cancer surgeries.
Colectomy
Unless cancer is very advanced, most tumors are removed by an operation known as colectomy:
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Colectomy involves removing the cancerous part of the colon and nearby lymph nodes.
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The surgeon then reconnects the intestine by a procedure known as
anastomosis
.
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If the surgeon cannot reconnect the intestine, usually because of infection or obstruction, a
colostomy
is performed. The need for colostomies is higher after surgery for rectal cancer. In most cases of colon cancer, colostomies are not needed.
The Surgical Approach.
The standard technique for a colectomy is open, invasive surgery. Laparoscopy, sometimes called “keyhole surgery,” is a less invasive method. Laparoscopy is still considered an investigational technique for treating colon cancer, but it is gaining more acceptance and showing good results in clinical trials.
Open Surgery:
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Open surgery uses a wide incision to open the patient's abdomen. The surgeon then performs the procedures with standard surgical instruments. This is the usual method for performing colectomy.
Laparoscopy:
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Laparoscopy uses a few small incisions through which the surgeon passes a fiber optic tube (laparoscope) containing a small camera or tiny instruments. It is generally used for early colon cancer (for tumors less than 2 centimeters or for well-defined tumors less than 3 centimeters).
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A 2004
New England Journal of Medicine
study found that patients who received laparoscopic colectomy had similar rates of surgical complications, cancer recurrence, and survival as those who received traditional open surgery. However, the patients who had laparoscopy recovered faster and did not need as many narcotic painkillers.
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Several 2005 studies indicated that laparoscopy works as well as conventional surgery for treatment of colon cancer. However, laparoscopy does not appear to be as effective for rectal cancer.
Other Investigative Measures.
Some investigators are testing expandable metal tube-like devices called stents to keep the intestine open. It may used before a procedure to allow bowel cleansing or it may be used for long-term use to keep open colons that are inoperable.
Colostomy
A colostomy is performed in order to bypass or remove the lower colon and rectum. The procedure generally involves creating a passage, called a
stoma,
through the abdominal wall that is connected to the colon. The feces pass through this passage and are eliminated. Patients must learn how to care for the stoma and keep the area sanitary.
A colostomy is usually by its location (for example in the sigmoid area) or by the have one opening (single-barreled), or there may be two loops opening through the skin (double-barreled).
Usually the colostomy is temporary and can be reversed by a second operation after about 3 - 6 months. It the rectum and sphincter muscles in the rectum need to be removed, the colostomy is permanent. Permanent colostomies are more common when the cancerous regions are within two 2 -3 centimeters of the anus. Fortunately, surgical advances and knowledge of the extent of safe margins are reducing the need for permanent colostomies.
Managing Permanent Colostomies.
In cases where the colostomy is permanent, the patient must wear a colostomy pouch, which sticks to the skin using a special glue. Pouches are available as one- or two-piece systems. The one-piece system is simpler, but the two piece system allows replacement of the pouch without removing the tape.
For best results, the pouch should be emptied when about one-third full. It should be replaced one or two times a week, depending on signs of leakage (itching or burning of the skin near the stoma). It is important to stress that the pouches are odor proof.
Surgical Treatments for Rectal Cancer
Surgical treatments for cancer in the rectum are complex since they involve muscles and tissue that are critical for urinary and sexual function.
Local Excision or Polypectomy for Early Stages.
In order to preserve the function of the anal sphincter and prevent the need for colostomy, Stage I and Stage II tumors may be removed by local excision, sometimes followed by chemotherapy and radiation. In this procedure, the tumor is cut out without removal of a major section of rectum. In some cases cancer recurs, but a second operation may be possible. Another treatment for early-stage rectal cancer called electrocoagulation, which destroys tumors using a high frequency electric current, is being tested but should be used only in the setting of clinical trials.
Radical Resection.
In about a third of cases of rectal cancer, the cancer occurs in the lower part of the rectum, where between 70 - 80% of cancers have spread beyond the rectal wall. In such cases, a radical resection is required, in which surrounding structures, including the sphincter muscles that control bowel movements, must often be removed.
The use of chemotherapy and radiation prior to surgery may prevent the need for permanent colostomy in some patients. This is an active area of clinical research, and current trials are under way to address this issue. An alternative technique called coloanal anastomosis reconstructs the area to avoid the need for colostomy, and may be appropriate in selected patients.
Total Mesorectal Excision.
Total mesorectal excision (TME) involves dissection and removal of the entire cancerous area of the rectum along with surrounding fatty regions where the lymph nodes are located (the mesorectum). When successful, TME preserves the sphincter muscle, reducing the need for a permanent colostomy. Increasing use of this procedure is resulting in lower recurrence rates, lower levels of impotence and incontinence, and better overall survival rates compared to other resection techniques. Some experts now recommend that it be the first choice for certain patients with locally advanced rectal cancer.
Combining chemotherapy and radiation either before or after TME is yielding promising long-term results and a low risk for local recurrence. There are many questions, however, and it is not clear which approach is better for specific patients.
Managing Side Effects and Psychological Repercussions
Side effects of colon surgery include:
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Sexual dysfunction. This is of particular concern. In general, colostomy does not usually affect sexual function. However, wide rectal surgery can cause short- or long-term sexual dysfunction. Sildenafil (Viagra) may help men who experience this after surgery.
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Irregular bowel movements.
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Gas and flatulence. Pouching filters are available to reduce gas. Certain foods produce more gas than others -- usually within 6 - 8 hours after ingestion for colostomy patients. They include beans, oat bran, most fruit, and certain vegetables (cabbage, cauliflower, Brussels sprouts, broccoli, and asparagus). To prevent swallowing air, patients should avoid sipping through straws, chewing gum, and chewing with their mouths open.
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Diarrhea.
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Bladder complications.
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Sense of urinary urgency.
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Fecal incontinence. Patients with rectal surgery have a higher risk for bowel dysfunction than those who had a colostomy.
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Complications in or around the stoma. These can occur early after surgery to many years after the procedure. They include skin infection or breakdown, hernias, narrowing of the stoma, bleeding, and collapse.
There are no dietary restrictions, although many patients avoid foods that can produce gas. Everyone should drink plenty of fluids and sufficient fiber.
The potential side effects of sexual and bowel dysfunction for colorectal surgical patients can be devastating, although many patients do very well and live normal productive lives. Positive emotions play a strong role in recovery. Patients who are depressed should discuss with a doctor all aspects of treatment that affect the quality of life and possibly seek support groups.
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Review Date: 3/6/2007
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Reviewed By: A.D.A.M. Editorial Team: Greg Juhn, M.T.P.W., David R. Eltz, Kelli A. Stacy. Previously reviewed by Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital (9/1/2006).
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