Rectal Cancer

Definition

Colon cancer develops in the large intestine (colon), the lower part of your digestive system. Rectal cancer develops in the rectum, which makes up the last several inches of your intestinal tract. Together, they're referred to as colorectal cancers.

Rectal cancer begins as small clumps of cells called polyps. Although most polyps are noncancerous (benign), some become cancerous over time. Regular screening to find and remove precancerous polyps can prevent rectal cancer from developing. Changes in your diet and lifestyle — such as healthy eating and increasing your physical activity — can help prevent polyps from forming, greatly reducing your risk of rectal cancer.


Symptoms
The symptoms of rectal cancer may be similar to those of other bowel diseases, like ulcerative colitis, Crohn's disease or even colon or colorectal cancers. Often there are no early symptoms of rectal cancer. However, as the cancer develops, rectal cancer symptoms may become more persistent and severe. Whereas, people with an inflammatory bowel disease (IBD), like ulcerative colitis or Crohn's disease, may experience periods of remission where the symptoms subside.

Rectal cancer signs

The development of tumors in the rectum or anal canal may change the consistency, shape or frequency of bowel movements. The severity of the symptoms may increase or more symptoms might arise as the cancer spreads throughout the rectum or into the colon. Rectal bleeding may make the stool bright red. A bleeding tumor may also change the color of the stools, sometimes making the stool very dark or tarry looking.

Rectal cancer signs related to bowel habit changes may include:

Diarrhea
Constipation
Not being able to completely empty the bowel
Change in the size or shape of stools (narrower than usual)
Bloody stool (either bright red or very dark)
General rectal cancer symptoms

Early stages of rectal cancer may have no symptoms. However, more systemic (body-wide) changes may result as the tumor goes deeper into the layers of tissues lining the rectum or if the cancer spreads (metastasizes) throughout the body.

Generalized symptoms of rectal cancer may include:

Pain in the rectum
Abdominal pain or discomfort
More frequent gas pains or stomach cramps
Feeling bloated or full
Change in appetite
Unintended weight loss
Fatigue or tiredness
There are several screening methods available that can detect polyps or cancer. A screening may make it possible to find the cancer before symptoms appear.


Rectal Cancer Causes: Who's at Risk?

The exact causes of rectal cancer are not known. However, studies show that the following risk factors of rectal cancer increase a person's chances of developing this disease:
Age. Colorectal cancer is more likely to occur as people get older. More than 90 percent of people with this disease are diagnosed after age 50. The average age at diagnosis is in the mid-60s. Diet. Studies suggest that diets high in fat (especially animal fat) and low in calcium, folate, and fiber may increase the risk of colorectal cancer. Also, some studies suggest that people who eat a diet very low in fruits and vegetables may have a higher risk of colorectal cancer. More research is needed to better understand how diet affects the risk of colorectal cancer.
Polyps. Polyps are benign growths on the inner wall of the colon and rectum. They are fairly common in people over age 50. Some types of polyps increase a person's risk of developing colorectal cancer.
A rare, inherited condition, called familial polyposis, causes hundreds of polyps to form in the colon and rectum. Unless this condition is treated, familial polyposis is almost certain to lead to rectal cancer.
Personal medical history. Research shows that women with a history of cancer of the ovary, uterus, or breast have a somewhat increased chance of developing colorectal cancer. Also, a person who has already had rectal cancer may develop this disease a second time.
Family medical history. First-degree relatives (parents, siblings, children) of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves, especially if the relative had the cancer at a young age. If many family members have had colorectal cancer, the chances increase even more.
Genetic alterations: Changes in certain genes increase the risk of colorectal cancer.
Hereditary nonpolyposis colon cancer (HNPCC) is the most common type of inherited (genetic) colorectal cancer. It accounts for about 2 percent of all colorectal cancer cases. It is caused by changes in an HNPCC gene. About 3 out of 4 people with an altered HNPCC gene develop colon cancer, and the average age at diagnosis of colon cancer is 44.

Familial adenomatous polyposis (FAP) is a rare, inherited condition in which hundreds of polyps form in the colon and rectum. It is caused by a change in a specific gene called APC. Unless familial adenomatous polyposis is treated, it usually leads to colorectal cancer by age 40. FAP accounts for less than 1 percent of all colorectal cancer cases.

Family members of people who have HNPCC or FAP can have genetic testing to check for specific genetic changes. For those who have changes in their genes, health care providers may suggest ways to try to reduce the risk of colorectal cancer, or to improve the detection of this disease. For adults with FAP, the doctor may recommend an operation to remove all or part of the colon and rectum.

Ulcerative colitis or Crohn's disease. A person who has had a condition that causes inflammation of the colon (such as ulcerative colitis or Crohn's disease) for many years is at increased risk of developing colorectal cancer.
Cigarette smoking. A person who smokes cigarettes may be at increased risk of developing polyps and colorectal cancer.


Diagnosis & Staging

If a person has any signs or symptoms of rectal cancer, the doctor must determine whether they are due to a diagnosis of rectal cancer or some other cause. The doctor asks about personal and family medical history and may do a physical exam.

If the physical exam and test results do not suggest rectal cancer, the doctor may decide that no further tests are needed and no rectal cancer treatment is necessary. However, the doctor may recommend a schedule for checkups. If tests show an abnormal area (such as a polyp), a biopsy to check for cancer cells may be necessary. Often, the abnormal tissue can be removed during colonoscopy or sigmoidoscopy. A pathologist checks the tissue for cancer cells using a microscope.

To help find the cause of symptoms, the doctor evaluates a person's medical history. The doctor also performs a physical exam and may order one or more diagnostic tests.
X-rays of the large intestine, such as the DCBE, can reveal polyps or other changes.

A sigmoidoscopy lets the doctor see inside the rectum and the lower colon and remove polyps or other abnormal tissue for examination under a microscope.

A colonoscopy lets the doctor see inside the rectum and the entire colon and remove polyps or other abnormal tissue for examination under a microscope.

A polypectomy is the removal of a polyp during a sigmoidoscopy or colonoscopy.

A biopsy is the removal of a tissue sample for examination under a microscope by a pathologist to make a diagnosis.

Stages of Rectal Cancer

If the diagnosis is rectal cancer, the doctor needs to learn the stage (or extent) of disease. Rectal cancer staging is a careful attempt to find out whether the cancer has spread and, if so, to what parts of the body. More tests may be performed to help determine the stage of the rectal cancer. Knowing the stage of the disease helps the doctor plan treatment. Rectal cancer staging may involve some of the following tests and procedures:
Blood tests: The doctor checks for carcinoembryonic antigen (CEA) and other substances in the blood. Some people who have colorectal cancer or other conditions have a high CEA level.
Colonoscopy: If a colonoscopy was not performed for diagnosis, the doctor examines the entire length of the colon and rectum with a colonoscope to check for other abnormal areas.
Endorectal ultrasound: An ultrasound probe is inserted into the rectum. The probe sends out sound waves that people cannot hear. The waves bounce off the rectum and nearby tissues, and a computer uses the echoes to create a picture. The picture shows how deep a rectal tumor has grown or whether the cancer has spread to lymph nodes or other nearby tissues.
Chest x-ray: X-rays of the chest can show whether cancer has spread to the lungs.
CT scan: An x-ray machine linked to a computer takes a series of detailed pictures of areas inside the body. The patient may receive an injection of dye. Tumors in the liver, lungs, or elsewhere in the body show up on the CT scan.

The doctor also may use other tests (such as MRI) to see whether the cancer has spread. Sometimes rectal cancer staging is not complete until the patient has surgery to remove the tumor. (Surgery for colorectal cancer is described in the "Treatment" section.)

Doctors describe colorectal cancer by the following stages:
Stage 0. The cancer is very early. It is found only in the innermost lining of the rectum.

Stage I. The cancer involves more of the inner wall of the rectum.

Stage II. The cancer has spread outside the rectum to nearby tissue, but not to the lymph nodes. (Lymph nodes are small, bean-shaped structures that are part of the body's immune system.)

Stage III. The cancer has spread to nearby lymph nodes, but not to other parts of the body.

Stage IV. The cancer has spread to other parts of the body. Rectal cancer tends to spread to the liver and/or lungs.

Recurrent. Recurrent cancer means the cancer has come back after treatment. The disease may recur in the colon or rectum or in another part of the body.


Preparing for Rectal Cancer Treatment

The doctor develops a rectal cancer treatment plan to fit each person's needs. Treatment for rectal cancer depends mainly on the location of the tumor in the rectum and the stage of the disease. The doctor can describe the treatment options and the expected results.
People do not need to ask all of their questions at once. They will have other chances to ask the doctor to explain things that are not clear and to ask for more information.

Methods of Rectal Cancer Treatment

Rectal cancer treatment may involve surgery, radiation therapy, or chemotherapy. Some people have a combination of treatments.
Colon cancer sometimes is treated differently from rectal cancer. Treatments for colon and rectal cancer are described separately.
At any stage of rectal cancer, treatments are available to control pain and other symptoms, and to relieve the side effects of therapy. This kind of treatment is called supportive care, symptom management, or palliative care.
People with rectal cancer may want to talk to the doctor about taking part in a clinical trial, a research study of new rectal cancer treatment methods. The section on "The Promise of Cancer Research" has more information about clinical trials.

Surgery for Rectal Cancer

Surgery is the most common rectal cancer treatment. It is a type of local therapy. It treats the cancer in the colon or rectum and the area close to the tumor.
A small malignant polyp may be removed from the colon or upper rectum with a colonoscope. Some small tumors in the lower rectum can be removed through the anus without a colonoscope.
For a larger cancer, the surgeon makes an incision into the abdomen to remove the tumor and part of the healthy colon or rectum. Some nearby lymph nodes also may be removed. The surgeon checks the rest of the intestine and the liver to see if the cancer has spread.
When a section of the colon or rectum is removed, the surgeon can usually reconnect the healthy parts. However, sometimes reconnection is not possible. In this case, the surgeon creates a new path for waste to leave the body. The surgeon makes an opening (a stoma) in the wall of the abdomen, connects the upper end of the intestine to the stoma, and closes the other end. The operation to create the stoma is called a colostomy. A flat bag fits over the stoma to collect waste, and a special adhesive holds it in place.
For most people who have a colostomy, it is temporary. It is needed only until the colon or rectum heals from surgery. After healing takes place, the surgeon reconnects the parts of the intestine and closes the stoma. Some people, especially those with a tumor in the lower rectum, need a permanent colostomy.

Rectal Cancer Chemotherapy

Chemotherapy uses anticancer drugs to kill cancer cells. It is called systemic therapy because it enters the bloodstream and can affect cancer cells throughout the body.
The patient may have chemotherapy alone or combined with surgery, radiation therapy, or both. Chemotherapy given before surgery is called neoadjuvant therapy. Chemotherapy before surgery may shrink a large tumor.
Chemotherapy treatment after surgery is called adjuvant therapy. Adjuvant therapy is used to destroy any remaining cancer cells and prevent the cancer from coming back in the colon or rectum, or elsewhere.
Chemotherapy is also used to treat people with advanced disease.
Anticancer drugs are usually given through a vein, but some also may be given by mouth. The patient may be treated in an outpatient part of the hospital, at the doctor's office, or at home. Rarely, a hospital stay may be needed.

Radiation Therapy for Rectal Cancer

Radiation therapy (also called radiotherapy) is local therapy. It uses high-energy rays to kill cancer cells. It affects cancer cells only in the treated area.
Doctors use two types of radiation therapy to treat cancer. Sometimes people receive both types:
External radiation: The radiation comes from a machine. Most patients go to the hospital or clinic for their treatment, generally 5 days a week for several weeks. In some cases, external radiation is given during surgery.
Internal radiation (implant radiation): The radiation comes from radioactive material placed in thin tubes put directly into or near the tumor. The patient stays in the hospital, and the implants generally remain in place for several days. Usually they are removed before the patient goes home.
Rectal Cancer Treatment Options

Most patients with rectal cancer are treated with surgery. Some have both surgery and chemotherapy. A colostomy is seldom needed for people with colon cancer.
Although radiation therapy is not commonly used to treat rectal cancer, sometimes it is used to relieve pain and other symptoms.