Rectal cancer is a disease in which malignant (cancer) cells form in the last 6 to 8 inches of the large intestine. The large intestine is a part of the digestive system and receives partially digested food from the small intestine. The large intestine helps to absorb water and additional nutrients. The rectum is between the colon and the anus where the waste is excreted.
Symptoms of Rectal Cancer
- Change in stool consistency (diarrhea or constipation)
- Bloody or dark stools
- Abdominal pain or cramps
- Loss of appetite and weight loss
Risk Factors of Rectal Cancer
Traits that increase your chance of getting a disease are called risk factors. However, this does not mean that you will get cancer; or that the absence of the risk factors means that you will not get cancer. Some risk factors are inherited (you are born with them).
Others are acquired as you age, and some of these you can control. If you think that you are at risk, it is a good idea to discuss this with your doctor.
Risk factors include:
- Being over the age of 40
- Change in bowel habits
- Having certain hereditary conditions, such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon cancer (HNPCC or Lynch syndrome)
- A diet high in fat and red meat and low in fiber, fruits and vegetables
- A previous history of colorectal (colon or rectal) cancer or advanced polyps
- Polyps (small pieces of bulging tissue) in the colon or rectum
- Cancer of the ovary, endometrium, or breast
- Having a parent, brother, sister, or child with a history of colorectal cancer or polyps
- Inflammatory bowel disease (such as Crohn’s disease or ulcerative colitis)
- How Rectal Cancer is Diagnosed
There are a variety of methods to diagnose rectal polyps and cancer. It may be found and staged with:
- Fecal occult blood tests – a stool sample is tested for trace amounts of blood that may not be visible. Although this may be due to an anal problem such as hemorrhoids, a positive test must always be followed by a full evaluation of the colon to search for the presence of cancer.
- Flexible Sigmoidoscopy – a shorter scope that is inserted through the anus to examine the rectum and lower one third of the colon. Suspicious lesions may be removed or sampled to check for cancer.
- Colonoscopy - a longer scope that may be used to view the entire rectum and colon. Suspicious lesions may similarly be removed or sampled to check for cancer. This is the most effective method for examining the entire colon.
- Double contrast barium enema – An x-ray test to examine the colon and rectum. Air and barium are inserted into the rectum and colon. A series of x-rays are obtained that may show abnormal masses. If this is positive, then a colonoscopy is usually performed to take samples for diagnosis. Although larger lesions are usually seen with a barium enema, many smaller lesions may be missed.
- Colonography (“virtual colonoscopy”) – a combination of a barium enema and CT scanning. A series of detailed x-rays are taken of the entire large intestine and then reconstructed on a computer. This is much more accurate that a simple barium enema, but small lesions may still be missed, and if the test is positive a colonoscopy must be performed to take samples for diagnosis.
Adenomas, or pre-cancerous polyps, of the colon and rectum are a common condition. Most colon and rectal cancers develop from the lining of the colon, the mucosa, and go through a series of genetic changes. This is called the polyp-cancer sequence. Most cancers arise from adenomatous polyps. If polyps can be found and removed, your risk of cancer will be substantially reduced.
Once a tumor is found, staging must be performed to determine how early or advanced the cancer is. This will help determine the best treatment approach. Staging starts with taking a sample of the tumor for the pathologist to examine under the microscope. Then one or more of the following tests may be recommended:
- CT (computerized tomography) scanning – CT x-ray studies are used as part of the staging of patients with colon and rectal cancer to see if there is spread beyond the wall of the bowel or if the cancer has spread to other organs such as the liver or lungs.
- PET-CT (positron emission tomography) scanning – This scan will help find masses that are likely to be cancerous by measuring how fast they use labeled sugars. Cancers use up sugars faster than most normal tissues.
- MRI (magnetic resonance imaging) scanning – MRI is useful when there is concern that the rectal tumor has penetrated beyond the rectal wall into surrounding tissues. It can also be used to detect for lymph node involvement.
- Endorectal ultrasound – This test looks at how deep into the wall of the rectum the tumor has penetrated, and whether any enlarged perirectal lymph nodes are present.
- Both the MRI and endorectal ultrasound are useful to determine whether rectal cancers may be treated with local excision as opposed to a larger surgery, and whether radiation and/or chemotherapy may be indicated.
Treatment Options for Rectal Cancer at Tufts Medical Center
The type of treatment for rectal cancer depends on the stage or extent of the cancer. Colon and rectal cancers are staged based on the depth of penetration through the wall, whether there is any spread to the lymph nodes around the rectum, and whether there is distant spread to other site such as the liver or lungs (metastases).
Rectal cancer diagnosed at early stages is treated with surgical removal of the cancer alone. More advanced cancers may be treated with radiation and chemotherapy first followed by surgical removal. Most patients can now be successfully treated without removing the anus (preserving the sphincter), so that fairly normal bowel function may be restored. A permanent colostomy (bag on the abdomen to collect stool) may be needed for the rectal cancers that are right next to or involving the anal muscles. Sphincter sparing surgery with anastomosis (re-connection of the bowel) is possible for most of our patients.
Large polyps and early cancers
Most adenomatous polyps may be removed during colonoscopy. However, the treatment of large adenomatous polyps and those in the upper rectum may be particularly challenging. Large rectal polyps and many early cancers may be treated with local excision, removing the lesion through the anus without any external incisions or scars.
Transanal endoscopic microsurgery (TEM) is a procedure that was developed in Germany and brought to the United States in 1990. To offer TEM surgery the hospital must have specially designed equipment and a surgeon who is skilled in this advanced technique. The major advantages of TEM include no hospital stay, rapid recovery at home, little pain, no external scars and normal anorectal function.
More advanced stages of rectal cancer are generally treated with radiation and chemotherapy followed by surgical resection. Additional chemotherapy is given after recovery from surgery as this practice results in the lowest recurrence rates.
Chemotherapy and radiation may be administered prior to and after surgery to reduce and eliminate remaining cancer cells. When chemotherapy is given with radiation, agents such as 5-fluorouracil (5FU) are used, and may be given using a prolonged infusion or by pill form. Patients who have the combination of chemotherapy and radiation before their surgery have a lower risk of the cancer coming back in the local area and have fewer side effects compared to those who have this treatment after surgery. So when possible, we typically offer chemo-radiation prior to surgery in patients with locally advanced tumors.
Radiation is delivered using 3D conformal external beam irradiation. This allows us to target the tumor and the lymph nodes more precisely and avoid and protect the unaffected bowel as much as possible. The radiation is given in small fractions of dose each day, Monday through Friday, over a period of about 5-6 weeks. Side effects are usually mild and include fatigue, decrease in appetite and loose stools. Our patients have close monitoring by our physicians, nurses and nutritionists while on this daily therapy to be sure to minimize these side effects.
Advanced disease including spread to the liver, lung and peritoneal (abdominal) cavity is treated with special protocols.
GI Oncology Tumor Conference
All patients undergoing therapy for colon and rectal cancer at Tufts Medical Center are discussed regularly at the combined GI Oncology Tumor Conference which is held weekly. Here your doctors who are experts in colon and rectal surgery, surgical oncology, medical oncology and radiation oncology as well as gastroenterology and nutrition, review your situation, make recommendations and follow your progress.
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