Source: Cancer Resource Room

What is Rectal Cancer?
Any cancer that starts in the rectum (end of the large intestine) is called rectal cancer.

These cancers are often grouped with the colon cancers and called colorectal cancers. Cancers are formed by abnormal cells that grow and divide without control. These cancer cells replace normal cells and form a tumor or lump. As a tumor gets bigger, it can grow into nearby tissues and organs. Cancer cells can spread to other parts of the body through the blood or lymph vessels. Most rectal cancers start in the cells that line the inside of the rectum. Tumor cells grow there, invade through the layers of the rectum, and spread to lymph nodes and other tissues. Colorectal cancer is one of the most common cancers in the US, with about 130,000 new cases a year.

What is the rectum and what does it do?
The rectum is the last part of the large intestine (colon).

Feces (stool or poop) is stored in the rectum until the next bowel movement. The important function of the rectum is to help control the release of feces. The anus and rectum join at a set of circular muscles called sphincters. The sphincters control the release of feces. Maintaining normal sphincter function is the greatest challenge in treating rectal cancer.
There are five layers of tissue that make up the rectum:

1. lining layer (lamina propria)
2. muscular layer for the lining (muscularis mucosa)
3. support tissue for lining layers (submucosa)
4. muscle (muscularis)
5. outside covering layer (serosa)

Rectal cancer usually starts in the lining layer. It grows larger and deeper through the other layers, spreading to nearby tissues and lymph nodes. The rectum can keep working even though a cancer has started in one part of it. This means a rectal cancer can get quite large or deep before it is diagnosed. Rectal cancers are more likely to cause noticeable symptoms than others tumors in the digestive system.

What are the symptoms of rectal cancer?
Symptoms caused by rectal cancer are from the tumor taking up space inside the rectum, from the loss of blood from the tumor, and from the tumor growing through the rectum into the nearby tissues. A tumor can cause a blockage or obstruction so the stool cannot pass by easily. This causes changes in the sizes and thickness of the feces, or causes alternating constipation and diarrhea. The cancer tissue can bleed into the rectum making the person anemic. The bleeding is seen on the feces or in the toilet. Some symptoms are caused by cancer cells invading into other tissues and putting pressure on nerves. When symptoms occur they include:

• rectal pain
• rectal bleeding
• change in bowel habits
• weight loss (without dieting)
• weakness or tiredness (due to anemia—a low blood count)
• bloody bowel movements
• buttock or perineal pain
• a feeling of not being done after bowel movement

These symptoms can have other causes and should be checked by a doctor.

How is rectal cancer diagnosed?
A patient’s medical history and physical exam are the first steps in making a diagnosis of any disease. The medical history includes many details of a person’s health. In particular, the history will focus on the digestive tract—changes in eating habits, changes in bowel movements, abdominal pain or bloating, and how food affects any of the symptoms. In the case of rectal cancer, the patient’s history may include information about other diseases such as:

• inflammatory bowel disease
• granulomatous colitis
• previous colorectal cancer or polyps
• radiation of the pelvis
• family history of polyps or colorectal cancer

The physical exam will focus on areas of discomfort in the rectum, the presence of a mass (a lump) in the rectum, enlarged lymph nodes, any weakness of the anal sphincter, and loss of sensation around the anus. The stool must be checked for blood. The rectum and anus need to be checked for lumps by digital (finger) exam.

After the history and physical exam, some diagnostic tests may be ordered. Blood tests and a chest x-ray check a patient’s general health. A blood count is done to check for anemia.

Special tests that are useful in diagnosing rectal cancer are:

1. CT scan—x-rays made in thin cross-sections of the pelvis. This set of x-rays can show a tumor in the lower colon and rectum, as well as its spread to nearby tissues and lymph nodes. This test is especially useful for finding disease in the rectum and nearby tissues, but not for finding affected lymph nodes.
2. Colonoscopy—this test uses a thin, flexible tube with a camera in it to look at the inside of the colon (large intestine) and rectum. The camera images are displayed on a TV monitor, allowing the doctor to see the inside of the entire large intestine. The colonoscope is passed through the anus and rectum into the colon and up through the large intestine. A biopsy can be taken of any tissue that looks abnormal. Lumps of tissue inside the colon called polyps can be removed. In preparation for the test, the patient drinks only liquids the day before, including a fluid that helps clean out the bowel. The procedure is done using sedation for relaxation. It is not a painful procedure and does not require anesthesia.
3. Endorectal ultrasound—a small probe is placed in the rectum and sound waves are emitted. As the sound waves pass through the tissues, a sensor on the lower abdomen picks up the signals and translates them into a picture. A radiologist can interpret the patterns to see the presence of a tumor, how far it has invaded the surrounding tissue, and whether or not there are enlarged lymph nodes nearby. The test is done in a radiology room. It is only a little uncomfortable, and does not require any medication.

What is a biopsy? What does it mean to a patient?
A biopsy is a small piece of tissue or group of cells used to diagnose a disease. The tissue is taken from a spot suspected of being abnormal. Then the biopsy tissue is looked at under a microscope by a pathologist. The diagnosis is based on the appearance of the tissue and cells. The biopsy result is used to decide a patient’s treatment.

What if the biopsy shows rectal cancer?
If the biopsy shows cancer, the next step is to find out how much disease there is. In particular, you need to know:

• how widespread is the disease in the rectum
• how many layers has it spread through
• has it spread beyond the rectum into the lymph nodes, into nearby tissues, or to distant lymph nodes and other organs

What tests are used to find the spread of rectal cancer?

• CT scans—these are x-rays that show cross-section pictures of the body. CT images let the radiologist see the abdominal organs in many ways, going across, as well as up and down, the body. An abdominal CT scan shows the stomach, lymph nodes, liver, gallbladder and bile ducts, pancreas, small and large intestines, kidneys, major blood vessels, and part of the spine. The patient may need to drink a contrast solution to help outline the digestive organs. An IV is used to give the patient contrast “dye” that travels through the blood. Contrast dye in the blood makes a person feel very warm for a brief time, and causes a sensation of needing to pee urgently. Both feelings pass quickly. CT scans are not painful but do require lying on a table for about 30 minutes.

The information about the patient, including the medical history, physical exam, blood tests, x-rays, special scans, and procedures, are used to describe the patient’s stage of disease and plan the best treatment for that disease.

What is the stage of a cancer? How is it determined?
The stage of a cancer describes how much cancer there is, what tissue it has invaded, and whether or not it spread to lymph nodes and other parts of the body. The higher the stage, the more complicated the disease. The stage is a combination of the size or extent of tumor growth, the number of lymph nodes involved, and the spread to other sites (metastases). For rectal cancer there are at least two systems for deciding the stage of the disease. One was developed by a surgeon named Dukes. It is based on the growth of tumor through the layers of the colon or rectum, invasion of nearby tissues, and spread to lymph nodes. The staging system used most today is the Tumor, Nodes, Metastasis system.

These are the TNM stages for adenocarcinoma of the colon or rectum:

• Stage 0: cancer cells are only in the lamina propria (lining layer). Cancer has not invaded the outer layers or lymph nodes. May be called, “carcinoma in situ.”
• Stage I: cancer has invaded from the lining layer into the submucosa or as far as the muscle layer. Cancer has not grown into any lymph nodes.
• Stage II: cancer has invaded the muscle layer, serosa, and nearby tissue, but has not spread to lymph nodes.
• Stage III: cancer has grown through all layers of the intestine, into nearby tissues, and to a few nearby (regional) lymph nodes. No tumor has traveled to distant nodes or organs.
• Stage IV: cancer has spread to other parts of the body (liver, lungs, bones, brain), with or without lymph node spread.

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