Surgery is a common treatment for rectal cancer. The type of operation used to remove the rectal cancer depends on the extent and location of the cancer. If the rectal cancer is located well above the anus, a low anterior resection (LAR) can be performed. This operation allows the patient to keep anal function and pass stools in a normal manner. If the rectal cancer is located close to the anus, sometimes the anus must be removed with the cancer in an operation called an abdominoperineal resection (APR). The patient must then use a colostomy bag. A colostomy is an opening where the large intestine is attached to the abdominal wall. A replaceable bag that encloses the colostomy is worn by the patient to collect stool.
Common symptoms include:
A change in your bowel habits, such as diarrhea, constipation or more-frequent bowel movements
Dark or red blood in stool
Mucus in stool
Painful bowel movements
Iron deficiency anemia
A feeling that your bowel doesn't empty completely
Unexplained weight loss
Weakness or fatigue
Rectal cancer occurs when healthy cells in the rectum develop errors in their DNA. In most cases, the cause of these errors is unknown.
Healthy cells grow and divide in an orderly way to keep your body functioning normally. But when a cell's DNA is damaged and becomes cancerous, cells continue to divide — even when new cells aren't needed. As the cells accumulate, they form a tumor.
With time, the cancer cells can grow to invade and destroy normal tissue nearby. And cancerous cells can travel to other parts of the body.
Inherited gene mutations that increase the risk of colon and rectal cancer
In some families, gene mutations passed from parents to children increase the risk of colorectal cancer. These mutations are involved in only a small percentage of rectal cancers. Some genes linked to rectal cancer increase an individual's risk of developing the disease, but they don't make it inevitable.
Two well-defined genetic colorectal cancer syndromes are:
Hereditary nonpolyposis colorectal cancer (HNPCC). HNPCC, also called Lynch syndrome, increases the risk of colon cancer and other cancers. People with HNPCC tend to develop colon cancer before age 50.
Familial adenomatous polyposis (FAP). FAP is a rare disorder that causes you to develop thousands of polyps in the lining of your colon and rectum. People with untreated FAP have a greatly increased risk of developing colon or rectal cancer before age 40.
FAP, HNPCC and other, rarer inherited colorectal cancer syndromes can be detected through genetic testing. If you're concerned about your family's history of colon cancer, talk to your doctor about whether your family history suggests you have a risk of these conditions.
The characteristics and lifestyle factors that increase your risk of rectal cancer are the same as those that increase your risk of colon cancer. They include:
Older age. The great majority of people diagnosed with colon and rectal cancer are older than 50. Colorectal cancer can occur in younger people, but it occurs much less frequently.
African-American descent. People of African ancestry born in the United States have a greater risk of colorectal cancer than do people of European ancestry.
A personal history of colorectal cancer or polyps. If you've already had rectal cancer, colon cancer or adenomatous polyps, you have a greater risk of colorectal cancer in the future.
Inflammatory bowel disease. Chronic inflammatory diseases of the colon and rectum, such as ulcerative colitis and Crohn's disease, increase your risk of colorectal cancer.
Inherited syndromes that increase colorectal cancer risk. Genetic syndromes passed through generations of your family can increase your risk of colorectal cancer. These syndromes include FAP and HNPCC.
Family history of colorectal cancer. You're more likely to develop colorectal cancer if you have a parent, sibling or child with the disease. If more than one family member has colon cancer or rectal cancer, your risk is even greater.
Dietary factors. Colorectal cancer may be associated with a diet low in vegetables and high in red meat, particularly when the meat is charred or well-done.
A sedentary lifestyle. If you're inactive, you're more likely to develop colorectal cancer. Getting regular physical activity may reduce your risk of colon cancer.
Diabetes. People with poorly controlled type 2 diabetes and insulin resistance may have an increased risk of colorectal cancer.
Obesity. People who are obese have an increased risk of colorectal cancer and an increased risk of dying of colon or rectal cancer when compared with people considered normal weight.
Smoking. People who smoke may have an increased risk of colon cancer.
Alcohol. Regularly drinking more than three alcoholic beverages a week may increase your risk of colorectal cancer.
Radiation therapy for previous cancer. Radiation therapy directed at the abdomen to treat previous cancers may increase the risk of colorectal cancer.
Surgery to remove the cancer is the most common treatment for rectal cancer. Surgery may also be done to treat a blocked bowel or cancer that has spread to other parts of the body.
LAR is a common treatment for rectal cancer when the cancer is located well above the anus. During a LAR, the entire rectal cancer, adjacent normal rectal tissue and surrounding lymph nodes are removed through an incision made in the lower abdomen. After the cancer is removed, the cut ends of the rectum are sewn back together. The passage of stool from the large intestine through the anus is therefore preserved. If the cancer is lower in the rectum, the cut end of the large bowel may be attached directly to the anus, a procedure known as colo-anal anastomosis. When a colo-anal anastomosis is performed, some surgeons will create a temporary colostomy in order to protect the delicate surgical connection of the large intestine to the anus. After the patient has recovered from the surgery, the temporary colostomy is removed and stool is again passed normally through the large intestine. The colon is resewn to the anus.
Despite undergoing complete surgical removal of rectal cancer, some patients may experience recurrence of their cancer. It is important to realize that some patients with rectal cancer already have small amounts of cancer that have spread outside the rectum and were not removed by surgery. These cancer cells are referred to as micrometastases and cannot be detected with any of the currently available tests. The presence of these microscopic areas of cancer causes the relapses that follow treatment with surgery alone. External beam radiation therapy and chemotherapy can be used to cleanse the body of micrometastases in order to improve the cure rate achieved with surgical removal of the cancer.
Patients undergoing an LAR may experience lower abdominal pain after the operation. Less common complications related to surgery include bleeding, infection and temporary difficulty with emptying the bladder. Some men may experience sexual dysfunction after surgery. In-hospital death occurs after LAR in less than 5% of patients. Patients should ask their surgeon to explain the various surgical complications and their frequency of occurrence at the hospital where the surgery will be performed.
APR is a common treatment for rectal cancer when the cancer is located close to the anus. During an APR, the entire rectal cancer, adjacent normal rectum, rectal sphincter or anus, and surrounding lymph nodes are removed through an incision in the lower abdomen and the perineum (the skin around the anus). Following removal of the cancer, the incision in the perineum is sewn shut. The cut end of the large intestine is attached to an opening in the abdominal wall, called a colostomy. This opening is covered with a bag, which serves to collect stool as it passes through the large intestine and through the colostomy. In contrast to a LAR, the colostomy is permanent.
Many patients would like to avoid a permanent colostomy. When the rectal cancer lies close to the sphincter or anus, an APR is typically recommended. In some instances, a more limited surgery can be used to avoid a colostomy, or radiation therapy can be used to shrink the rectal cancer prior to surgery allowing the patient to maintain control of bowel function. Some small rectal cancers that lie close to the anus can be removed with less extensive surgery called a local excision. Not all patients can undergo a local excision (see Local Excision below).
Patients undergoing an APR may experience lower abdominal pain after the operation. Less common complications related to surgery include bleeding, infection, slow wound healing and temporary difficulty with emptying the bladder. Some men may experience sexual dysfunction after surgery. In-hospital death occurs after APR in less than 5% of patients. Patients should ask the surgeon to explain the various surgical complications and their frequency of occurrence at the hospital where the surgery will be performed.
The rectal sphincter is the circular muscle that controls defecation. If damaged, patients lose control of bowel function. Sphincter-sparing treatment refers to cancer therapy that avoids removal of the anal sphincter for rectal cancers that lie close to the anus. The standard surgical procedure used to remove rectal cancer that lies close to the anus is an abdominoperineal resection (APR). Following an APR procedure, the anus is removed with the cancer, and the cut end of the large bowel is attached to the abdominal wall to form a colostomy. The colostomy is covered by a bag, which collects stool as it empties from the bowel. Because of the inconvenience of a colostomy, physicians are using sphincter-sparing treatments that allow the patient to preserve function of the anus. Sphincter-sparing treatment for rectal cancer involves limited surgery, often followed by a combination of chemotherapy and radiation therapy. The limited surgery is designed to remove the cancer and a small rim of normal bowel, but not the anus. The surgery may be performed through the anus (transanal excision) or through the coccyx (transcoccygeal) or the tailbone. A transanal excision can be performed for small cancers that lie close (within 2 inches) to the anus. Other small cancers higher in the rectum can be removed with a transcoccygeal excision.
Limited surgery can be performed to remove the cancer and preserve the anus and prevent the complications that may occur with more extensive LAR or APR surgeries. The limited surgery is designed to remove the cancer and a small rim of normal bowel, but not the anus. The surgery may be performed through the anus (transanal excision) or through the coccyx (transcoccygeal) or the tailbone. A transanal excision can be performed for small cancers that lie close (typically within 2 inches) to the anus. Other small cancers higher in the rectum can be removed with a transcoccygeal excision.
For limited surgery to be effective, the entire cancer with a rim of normal tissue must be removed. Patients with cancers that are larger, more deeply invading, or appear aggressive under the microscope are better treated with traditional surgery. In order to improve the cure rates after limited surgery alone, a combination of chemotherapy and radiation therapy is often administered for cancers that have grown into the muscular wall of the rectum.
Patients undergoing limited surgery may experience pain in the region of the perineum or tailbone. Less common complications related to surgery include bleeding, infection, and difficulty with healing of the rectal wall. In-hospital fatality is very rare after limited surgery.