GENERAL BACKGROUND
Large bowel cancer will affect approximately 180,000 persons in the United States this year. It will cause about 64,000 deaths. The rate or incidence of large bowel cancer in men and women is approximately equal. The risk of large bowel cancer is increased in patients who have what are called inflammatory bowel diseases, such as ulcerative colitis or regional enteritis.

Carcinoma of the large bowel is also increased in patients who have syndromes in which polyps are found in the bowel. In the first half of the 20th century most large bowel tumors were found in the area of the rectum and the sigmoid colon, which are the lower portions of the large bowel on the left side of the abdomen. Over the last 30 to 50 years, more cancers have been found in the right side of the colon.

This has probably been due to better surveillance of patients with a history of colon cancer or a family history of colon cancer. This allows for the earlier discovery of polyps which are known to be precancerous lesions. The removal of such polyps can therefore decrease the risk of cancer in the large bowel.

Evidence seems to indicate that the intake of fiber in the diet will have a preventive role with regard to large bowel cancer. There is a low incidence of bowel cancer in countries where dietary fiber makes up a large part of the patient's daily food intake. There is also a strong correlation between the amount of fat in the diet and the incidence of colon cancer.

Some of the preventive measures which can be taken are routine surveillance colonoscopy after the age of 50, especially in those patients with a strong family history of colon or rectal cancer and in those patients in whom a polyp has been found on a previous examination. Also, the intake of dietary fiber, the use of selenium additives, and the intake of aspirin have all been associated with decreased risks of polyps and bowel cancer.

DIAGNOSIS | Back to Top
The most common presenting feature in patients with rectal and low sigmoid colon cancer is melena (dark stools or blood in the stools). Abdominal pain is the most common feature in patients who have colon cancer above these areas. Other features include changes in bowel habits, nausea, vomiting, weakness, and an abdominal mass. Sometimes colon cancer is found in patients who have anemia due to a gradual blood loss over a prolonged period of time.

Diagnostically, the most common study today is the colonoscopy. Very seldom are barium enemas utilized any longer in the diagnostic workup of colon cancer. The colonoscopy allows the endoscopist (the physician doing the procedure) to measure the distance from the anus to the lesion and to describe the lesion in full, as well as to biopsy the lesion.

Once the diagnosis of colon malignancy has been made, CT scans are performed of the lungs, abdomen, and pelvis to rule out metastatic disease or lymphatic disease somewhat distant from the colon lesion. Also, preoperatively a level of carcinoembryonic antigen (CEA) is determined from the blood. CEA is an independent prognostic factor in large bowel cancer. If it is elevated before an operative procedure and decreases after the removal of the colon cancer, it is a reliable factor for use in the follow-up of patients with cancer. It if stays low, the cancer is probably not recurring; if it is high, the cancer may be coming back.

Unfortunately, about 75 percent of patients who do have recurrences of their colon and rectal cancers after operative resection will have other symptoms before their CEA rises. The 25 percent of patients who have a rising CEA before any symptoms are more likely to be cured of their recurrence.

TREATMENT | Back to Top
The primary treatment for patients with cancer in the colon and the rectum is a surgical resection. Surgery and chemotherapy are the primary treatments for those patients whose disease is involving the colon or the rectosigmoid colon. Chemotherapy is utilized when lymph nodes are found to contain tumor in the resection specimen.
In carcinoma of the rectum, surgery is also the treatment of choice.

The use of radiation in carcinoma of the rectum has undergone several revisions over the past 40 years. In the late 1960s and early 1970s, preoperative radiation was quite common. In Europe, rapid courses of high-dose radiation delivered in one week led to increases in survival rates in patients with rectal cancer. It was also noted that there was a decrease in the number of patients in whom there was a recurrence of the disease in the pelvis.

In the United States, preoperative radiation at that time involved approximately 25 treatments over five weeks, with the surgery delayed for four or fives weeks to allow the tumor to regress or shrink as far as it might. This time period was also crucial in the initiation of surgery because the fibrosis from the radiation had not occurred, and the swelling and inflammation from the radiation had subsided, therefore making the operative field ideal for the resecting surgeon.

Again, it was found this type of radiation significantly decreased the number of patients who were found to have positive lymph nodes at the time of surgery. It also decreased the local recurrence rate of the tumor in the pelvis after surgery, and it increased the overall survival of patients with carcinoma of the rectum.

In the middle 1970s or early 1980s, a change in the pattern of treatment began. A study had been performed by the Gastrointestinal Study Group which determined the combination of a chemotherapy drug called 5-Fluorouracil (5-FU) used along with radiation considerably decreased the incidence of local recurrence and increased patient survival when it was given after operative intervention in carcinoma of the rectum. This became the standard of therapy in carcinomas of the rectum for 20 years.

The study found those patients who had positive lymph nodes or who had extension of disease through the rectal wall into the fat surrounding the rectum within the pelvis had a significant decease in the local recurrence rate of the tumor and also had an increase in survival. For instance, patients who at surgery had been found to have disease through the bowel wall and in lymph nodes were noted to have a 70 to 80 percent local recurrence rate when radiation and chemotherapy were not used.

With the use of radiation and chemotherapy, the occurrence of new tumor in the pelvis after surgery decreased to 15 percent. Also, it was found that incidence of distant metastases was also somewhat decreased by the use of 5-FU chemotherapy.

One of the more feared results of surgery in patients with carcinoma of the rectum is the need for a colostomy. Over the past 20 years as surgical techniques have improved, surgeons have been able to spare the rectum and anus more frequently than they have in the past. Today, only about 20 percent of the patients actually need to have a colostomy. This really depends on the closeness of the tumor to the anus. Studies in the Philadelphia area at Thomas Jefferson University indicated preoperative radiation and chemotherapy could shrink rectal tumors significantly and allow surgeons to more often preserve the anus.

These patients frequently had excellent sphincter control and relatively normal bowel movements. This type of treatment also demonstrated a 10 to 15 percent incidence of complete disappearance of the tumor, with no evidence of the tumor found at the time of the operative procedure.

With improvements in surgical techniques and the benefit of preoperative radiation having been seen 30 years ago and more frequently in the anal preservation era, it was determined, patients should possibly be more frequently treated with preoperative radiation and chemotherapy for their carcinoma of the rectum.

Today, patients have staging with CT scans of the lungs, abdomen, and pelvis. If no evidence of metastatic disease is seen, those patients will have preoperative 5-FU and radiation therapy, especially when the tumor is located close to the anal area. This radiation encompasses about 31 treatments over a period of six weeks and will be described below.

Approximately four to six weeks after the preoperative chemo-radiation, the surgical procedure of choice is performed.
When patients have been diagnosed with a rectal cancer, they are often referred to the medical oncologist and the radiation oncologist almost simultaneously.

Treatment plans are made to coordinate systemic chemotherapy with the planned radiation. Initially upon seeing the radiation oncologist, a complete history and physical examination will be performed by the physician. A comprehensive discussion then takes place of the radiation treatment and the pertinent side effects and complications, as well as the expected results.

Once it has been determined that radiation is needed in the treatment of a patient with rectal cancer, a treatment simulation and CT therapy plan are scheduled.

Treatment simulation is a procedure in which a patient is placed in the treatment position and fluoroscopy is performed to set the region of radiation treatment. Following this, films are taken to verify the areas to be treated. Marks are placed on the patient, which should remain during the course of radiation. These are specific in that they allow precise patient positioning during the course of treatment so only the areas of tumor and lymph nodes which require treatment are in fact treated on a daily basis. Following the simulation, a CT is performed of the area to be treated.

The purpose of this is to identify the area of tumor in those patients who are treated preoperatively and to identify specific structures, such as the bladder, ovaries, and the small bowel, in patients who have had previous surgery. It is important to understand the position of the small bowel since this is the most sensitive tissue to radiation besides the bone marrow.

Once the CT scan has been completed, the data is transferred electronically to the treatment planning system which helps us to design the radiation portals to be utilized in the patient's therapy and to focus the radiation doses on those areas most likely to have recurrent disease. These areas generally are in the region of the pelvis, near the area of the primary tumor or the area of previous surgical resection when disease has spread through the bowel wall or involves lymph nodes.

Generally, in our Clinic the patients are treated in the supine position (on their backs). Occasionally, if it is difficult to spare small bowel from the treatment field, the patient will be treated in the prone position (lying on the stomach). During the initial five weeks of treatment, the entire pelvis is treated from at least four areas (front, back, and both sides). Following that, the radiation beams are decreased to treat the most frequent area of local recurrence, which is in front of the sacral bone. Generally, this is a three-treatment boost of radiation through right and left lateral and posterior fields. Finally, if the patient has not had surgery and is being treated preoperatively, an additional boost of three treatments is given through smaller lateral fields just to the area of the tumor. Approximately four to six weeks after the radiation is completed, the surgeon will perform the operation in those patients receiving preoperative radiation.

Chemotherapy during radiation can be delivered in several ways. At times, it is given once a week or sometimes five days a week during weeks one and four of treatment. Sometimes, the chemotherapy is delivered by continuous infusion using a central line and a device which constantly infuses the chemotherapy during the entire course of radiation.

The most frequent chemotherapy used is 5-FU, but now other regimens, including Leucovorin and a drug called CPT11 are being used. Also, there is some data to indicate that an oral form of 5-FU chemotherapy known as Xeloda can be used along with a drug called Taxotere which is given intravenously.

Postoperative radiation therapy is delivered only to those patients who have disease spreading through the rectal wall into the surrounding fat or in those patients who have evidence of rectal cancer in the lymph nodes which have been resected. If patients do not have extension through the bowel wall or positive lymph nodes, they are not generally treated with postoperative radiation therapy for their carcinoma of the rectum.

Preoperative chemo-radiation is generally delivered in those patients who have a tumor which is very close to the anus or in those patients who have large, bulky tumors which may be attached or nearly attached to surrounding structures as noted on the pretreatment workup.

SIDE EFFECTS | Back to Top
The side effects of radiation, whether preoperative or postoperative, are generally reasonably minor. Patients may experience some mild pink discoloration of their skin. There will be some loss of pubic hair, which will not be permanent. Patients may experience some mild urinary discomfort if they do not drink adequate amounts of fluids.

There will probably be some diarrhea during the course of therapy. This type of diarrhea is easily controlled by over-the-counter medications, such as Imodium AD. If patients develop diarrhea during their course of therapy, they are given a diet sheet by the nurses to help them with the control of their stools.

Fatigue may also become a factor during treatment. Patients generally are not severely fatigued, but they might have mild tiredness as time goes on through the treatment. They should not give up physical activity, but if they become tired they should take a nap during the day or sleep more at night. In patients who have their anus removed at surgery and who have a colostomy, the area of the anal surgery must be treated in an attempt to prevent local recurrence of tumor in the region.

This will cause significant skin reaction at the site of the anal surgery. There will probably be significant redness and possibly loss of skin in this area during the latter portion of the radiation. Sitz baths, various creams and lotions, and pain medications are prescribed by the radiation oncologist to help the patients through this time. Once the treatment is over, the area usually heals within 10 to 14 days.

Long-term complications of treatment are generally related to the bowel. As stated previously, the small bowel is one of the most sensitive areas to radiation treatment. Patients who have preoperative radiation and have never had abdominal surgery generally will not have small bowel problems in the long run. This is because the bowel is floating around in the abdomen, and the same pieces of bowel are never treated on consecutive days. Unfortunately, in patients who have had previous surgery, there are scars inside the abdomen as there are outside on the skin. These scars are called "adhesions" and will hold the small bowel in place.

On the CT scan the small bowel can be seen, and we attempt to keep as much small bowel as possible out of the radiation beam. Despite this, there is a 5 to 7 percent chance that the patients will have irritation of the small bowel sometime after 12 months following the radiation. This might present itself as abdominal cramping and pain, significant diarrhea, or bowel obstruction. Generally, these symptoms will require hospitalization for the passage of a tube into the stomach to rest the bowel. At times, a resection (removal) of small bowel affected by radiation is needed.

Another possible, but rare long-term complication of treatment is swelling of the lower extremities. This is highly unusual with modern radiation therapy but has been reported in the past. This is caused by the surgical resection of lymph nodes and the subsequent treatment of the lymphatic vessels; this is caused by scarring in the area which prevents the fluid from getting out of the legs.

THE FUTURE | Back to Top
Overall, carcinoma of the colon and rectum is being found more frequently and earlier than it has been in the past. During your course of radiation, you will be interviewed and possibly examined by the physician at least one time per week. You will be asked about symptoms daily by the radiation therapist giving you your treatment. He or she will ask how you are doing and possibly ask about specific problems which might be occurring. If you have a problem at any time, please let your radiation therapist know so that he or she can have you seen by a radiation oncologist. We wish to relieve symptoms as much as possible during the course of treatment, but you must understand that we may not be able to keep all of your symptoms away. We may be able to lessen them, but some symptoms will be present during the course of treatment.
We will be glad to answer questions for you any time during the treatment.