The incidence of adenocarcinoma of the colon and rectum increases with age; over 90 percent occurs in individuals over the age of 40, with the peak incidence in the 60's. Approximately 75 percent of the cancer in this part of the body occurs in that part of the colon which is directly accessible to examination by the physician. Cancer of the rectum occurs more frequently in men; cancer of the colon in women. This malignancy causes the largest number of deaths in sites common to both men and women. Most patients have relatively late disease by the time they go to the physician.

Symptoms

The symptoms are change in bowel habits, flatus, bleeding, and pain. When these occur the individual should immediately seek medical attention. However, all too frequently the person procrastinates for 6 months or more before seeking proper medical care, blaming his symptoms on dietary indiscretions or on hemorrhoids. To improve the outcome for those with cancer of the colon and rectum we must teach people to pay attention to these symptoms and treat them seriously.

Treatment

Surgical excision of the tumor; the extent depends upon the location of the tumor and the extent of metastases. The usual types of surgery are:

1. Abdominoperineal Resection

An abdominal colostomy is established and the lower portion of the bowel and anus are removed through an opening which is made in the perineum. In most instances the perineal opening is left open and with the passage of time much of the area fills in to become solid. The alternate procedure is to sew up the perineum at the time of operation. (Figure 7).

2. Abdominoperineal Proctosigmoidectomy

With preservation of the sphincter. There is no colostomy as the upper colon is pulled down to unite with the upper margin of the anal sphincter. This is sometimes possible when the neoplasm is in the midportion or upper portion of the rectum. The result is a normal appearing anus and perineum. This is sometimes called the "pull through" operation.

3. Resection and End to End Anastomosis

The segment of the colon containing the cancer is resected and removed. The two healthy remaining sections of the colon are brought together so that continuity of the bowel is re-established. There is no colostomy and no opening in the perineum.

4. Double Barrel Colostomy

No resection is done. The bowel is exteriorized and there are two openings on the abdominal wall- one for the upper bowel and one for the lower. This procedure may be done as a temporary decompression measure when obstruction of the bowel occurs or as a palliative procedure for an inoperable lesion. When the colostomy is done for palliative purposes the most distal site available is selected (the sigmoid if possible) so as to retain as much functioning bowel as possible. This type of colostomy is done in one of two ways. Sometimes the bowel is opened at the time of surgery and a tube is placed into the proximal loop which will later become the proximal stoma. Sometimes the bowel is exteriorized but is not opened until 12 to 24 hours postoperatively, usually by cautery. (Figure 8).

5. Short Circuiting Operation

The bowel above an unresectable lesion may be anastomosed, side to side, to a segment distal to the lesion if such is available.

In addition to surgery, other methods of treatment for incurable cancer of the colon and rectum sometimes include radiation and chemotherapy. Usually these are less effective than in some other body areas. Another means of palliation is repeated fulguration of lower rectal lesions to keep an opening through a tumor which is filling the rectum.