Bowel Cancer: Types, Symptoms, Causes, Stages, Diagnosis, Treatment and Prevention

The most extended section of the gastrointestinal tract (GI) is the small intestine, three and a half times the length of the body, and connects the stomach with the large intestine.

It is the type of cancer where cancer cells are present in the small or large intestine. The intestines are part of the body’s gastrointestinal (digestive) system.

Cancer that develops in the large intestine is called colorectal cancer.

The small intestine digests and absorbs nutrients. It is divided into the duodenum, the jejunum, and the ileum. Most types of small bowel cancer develop in the duodenum.

Cancer in the small intestine

Types of intestinal cancer

Among the main types of small bowel cancer are:

  • Adenocarcinomas – the most common type of small bowel cancer – usually develop in the cells that line the small intestine walls. This type of cancer often develops from small, benign (non-cancerous) growths called polyps.
  • Sarcoma: is a type of intestinal cancer that develops in the connective tissue of the small intestine.
  • Gastrointestinal stromal tumors: are variants of soft tissue sarcoma.
  • Carcinoid tumors:  are formed in the lining of the intestines and are often slow-growing.
  • Lymphomas: are a disease of the immune system that can originate inside the intestines.


The small intestine is a long, coiled tube that channels digested food from the stomach into the colon (the large intestine).

On the way, the digested material is further broken down, and nutrients and amino acids are absorbed.


Abdominal pain accompanied by nausea and vomiting may indicate intestinal obstruction. In this case, you may require immediate medical attention. Often, surgery is necessary to eliminate the blockage.

In rare cases, the tumor can cause a perforation in the intestinal wall, causing the contents to spill into the abdominal cavity. This will also cause intense pain and vomiting.

Symptoms of small bowel cancer may be signs of other gastrointestinal conditions or diseases.

Often, however, small tumors may not cause any apparent symptoms.

Sometimes cancer can be found by chance during another procedure or unrelated surgery.

The following are some of the most recurrent symptoms of small bowel cancer:

  • Abdominal pain.
  • Unexplained weight loss
  • Weakness or fatigue: sometimes as a result of anemia.
  • Stools with blood or tars: due to bleeding tumors.
  • A noticeable bulge in the abdomen.

However, intestinal symptoms are often vague and difficult to diagnose.

Risk factor’s

  • Age: According to the American Cancer Society, the average age at diagnosis is 67.
  • Gender: Men are more likely to develop the disease than women.
  • Hereditary condition: Although most small bowel cancers occur without a known hereditary bond, some inherited conditions can be higher risk.
  • Poliposis adenomatosa familiar (FAP).
  • Hereditary nonpolyposis colorectal cancer (HNPCC): is also called Lynch syndrome.
  • Canz-Jeghers Syndrome (PJS).
  • Cystic fibrosis (CF).
  • People with multiple endocrine neoplasias, type I (MEN1), or defects in the NF1 gene (neurofibromatosis type 1): can develop benign tumors in the small intestine at risk of becoming malignant carcinoid tumors.
  • Gardner syndrome: Although there is an increased risk of colon cancer, this disease is considered a risk factor for small bowel sarcomas.
  • Enfermedad de Von Recklinghausen.
  • La neurofibromatosis.
  • Tobacco and alcohol use:  Some research suggests that smoking and drinking may also be associated with developing small bowel cancer.
  • Diet: Eating a high-fat diet can be a risk factor for small bowel cancer.
  • Chemical exposure: certain chemicals, such as vinyl chloride, dioxins, and high doses of herbicides containing phenoxy acetic acid, are considered risk factors for intestinal cancer for certain sarcomas.
Other conditions
  • Gastrointestinal diseases: certain diseases that affect the gastrointestinal tract may increase the risk of developing bowel cancer—for example, Crohn’s disease or if you have had colon cancer before.
  • Lymphedema: damage to the lymphatic vessels or an infection can cause the accumulation of lymphatic fluid. This can increase your risk of developing a small bowel sarcoma.


Deciding for an appropriate treatment begins by observing the stage or progression of the disease.

The stage of intestinal cancer is one of the most critical factors in evaluating treatment options.

Some cancers, such as carcinoid tumors, do not have a standard staging system.

The stages of intestinal cancer described here are the most common adenocarcinomas and are defined using the TNM system.

The combined categories, T, N, and M, create stages 0 to IV:

  • A tumor (T): tumors are classified on a scale of 0 to 4, where T0 indicates no evidence that the primary tumor expands in the local tissue, and the increasing number (T1 to T4) describes the spread of the tumor. Tumor towards and the intestinal wall. Carcinoma in situ is described as early cancer that has not gone beyond the mucosa.
  • Node (N): If cancer is found in the lymph nodes, the number of cancer cells found is rated N1 or N2. N0 indicates the conditions in which cancer has not spread to the lymph nodes.
  • Metastasis (M): when cancer has spread, the acronym M1 indicates it. Otherwise, M0 is used if there are no signs of metastasis.
Stage 0

Cancer has not expanded beyond the mucosa. (This, N0, M0).

Etapa I

The disease has grown beyond the mucosa but has not spread beyond the small intestine to other sites or lymph nodes (T1, N0, M0 or T2, N0, M0).

Stage II

Cancer has expanded through the intestinal wall. At this stage, it may or may not have reached nearby organs.

There is no evidence of disease spread to lymph nodes or distant sites (T3, N0, M0).

Stage III

In stage III intestinal cancer, the disease has metastasized to nearby lymph nodes. The tumor can be any size (T1 to T4).

Cancer may or may not have reached nearby organs. Distant sites such as the lung or liver are not affected (T1, N1, M0).

Etapa IV

Cancer can be any size and has spread throughout the body to distant sites such as the liver, lung, or lining of the abdominal cavity (for example, any T, any N, M1).

Colon cancer

Colorectal cancer, also known as large bowel cancer, colon cancer, or rectal cancer, is any cancer that affects the colon and rectum.

Most cases of colon cancer begin as small, non-cancerous (benign) groups of cells called adenomatous polyps.

Polyps can be small and produce few, if any, symptoms.

For this reason, doctors recommend periodic screening tests to help prevent colon cancer by identifying and eliminating polyps before they turn into cancer.


  • A change in your bowel habits: including diarrhea or constipation or a change in the consistency of your stools, which lasts for more than four weeks.
  • Rectal bleeding or blood in your stool.
  • Persistent abdominal discomfort: like cramps, gas, or pain.
  • A feeling that your bowel does not empty.
  • Weakness or fatigue
  • Unexplained weight loss

Many people with colon cancer do not experience symptoms in the early stages of the disease.

If the symptoms appear, they are likely to vary, depending on the size of the cancer and the location in the large intestine.


  • Age: Increasing age is the leading risk factor for colorectal cancer. About 90% of colorectal cancers are diagnosed after age 50.
  • Race: African Americans have a higher incidence of colorectal cancer than people of other races.
  • Diet: It has been shown in numerous research studies that high-fat diets have a high predisposition to generate colorectal cancer.
  • Obesity: Being overweight (especially having a considerable waste) increases the risk of colon cancer in both men and women, but the link seems to be stronger in men.
  • Lack of physical activity
  • Cigarette consumption: Smoking is a well-known cause of lung cancer, but it is also related to other types of cancer, such as colorectal cancer.
  • Exaggerated intake of alcoholic beverages.
  • Have a personal history of colorectal polyps or colorectal cancer.
  • History of inflammatory bowel disease: If you have inflammatory bowel disease (IBD), including ulcerative colitis or Crohn’s disease, your risk of colorectal cancer increases.
  • Have a family history of colorectal cancer or adenomatous polyps.
  • Having a hereditary syndrome: About 5% to 10% of people who develop colorectal cancer have inherited genetic changes (mutations) that can cause family cancer syndromes and lead to contracting the disease.
  • Night work: It is believed that this could be due to changes in the body’s body’s melatonin levels (a hormone that responds to changes in light).
  • Previous cancer treatments: Some studies have found that men who survive testicular cancer have a higher rate of colorectal cancer and some other cancers. This could be due to their treatments, such as radiation therapy.
  • People with type 2 diabetes: People with type 2 diabetes have an increased risk of developing colorectal cancer since both share the same risk factors (such as being overweight and physical inactivity).
  • Gardner syndrome: People with this syndrome often develop many polyps throughout the GI tract, particularly in the colon.


Stage 0

This is the earliest stage when the cancer is still inside the colon or rectum’s mucosa or inner layer.

Stage 1

Cancer has grown through the inner layer of the colon or rectum, but it has not yet spread beyond the wall of the rectum or colon.

Stage 2

Cancer has grown through or into the wall of the colon or rectum but has not yet reached the nearby lymph nodes.

Stage 3

Cancer has invaded nearby lymph nodes but has not yet affected other body parts.

Stage 4

Cancer has spread to other body parts, including other organs, such as the liver, the lining of the abdominal cavity, the lung, or the ovaries.


For cancer diagnosis, there are multiple options of tests to find or diagnose it.

Tests are also done to determine if cancer has spread to another body part from where it started.

A biopsy is the only sure way for the doctor to know if an area of ​​the body has cancer for most types of cancer.

In a biopsy, the doctor takes a small tissue sample to be analyzed in a laboratory.

If a biopsy is not possible, the doctor may suggest other tests to help you make a diagnosis.

Additionally, the following tests can be used to diagnose bowel cancer:

  • Blood tests: A test of the number of red blood cells in the blood can indicate if you are anemic. Anemia can result from bleeding, liver problems, or poor nutrition related to cancer.
  • X-ray: X- rays of the gastrointestinal system can be taken. Sometimes, the person will take a barium substance, which outlines the entire gastrointestinal system on the x-ray; this will help the doctor see tumors or other abnormal areas.
  • Endoscopy: A thin tube with a camera on the end is used to visualize the duodenum and check for abnormal areas. This procedure can be done to determine if the disease has spread.
  • Colonoscopy: is similar to the traditional endoscopy described above, except that the endoscope enters the body through the anus and rectum into the colon and lower part of the small intestine.
  • Computed tomography (CT or CAT):  creates a three-dimensional image of the inside of the body from different angles, which allows us to measure the size of the tumor and verify if there is cancer spread to other organs.
  •  A positron emission tomography (PET) scan is a procedure in which positron emission tomography and computed tomography are performed simultaneously. It involves injecting radioactive glucose to see where in the body it concentrates most since malignant tumors need more glucose than normal cells.
  • Laparotomy:  In this procedure, a surgical incision is made in the abdomen to detect diseases. Sometimes, tissue samples are taken, and surgery is often performed simultaneously to remove the tumor.


The options and treatment recommendations depend on several factors, including the type and stage of cancer, the possible side effects, the patient’s preferences, and overall health.


The surgery involves removing the tumor and some surrounding healthy tissue during an operation. It is the most common treatment for bowel cancer.

Depending on the extent of the surgery, it may be necessary to follow a special diet with medications and supplements to aid digestion.

Surgery’s side effects may include pain and tenderness in the area of ​​the operation.

The operation can also cause constipation or diarrhea, which usually disappears.


Chemotherapy is the use of drugs to destroy cancer cells, usually by stopping the ability of cancer cells to grow and divide.

Because chemotherapy affects both normal and cancerous cells, many people experience the side effects of the treatment.

The side effects of chemotherapy depend on the individual and the dose used but may include loss of appetite, nausea, vomiting, infection risk, hair loss, fatigue, and diarrhea.

These side effects usually go away once the treatment ends.

Radiation therapy

Radiation therapy uses high-energy x-rays or other particles to destroy cancer cells.

Radiation therapy is most commonly used as a palliative treatment to help relieve side effects.

The most common radiation treatment type is external beam radiation, which is radiation delivered from a machine outside the body.

When radiation therapy is given with implants, internal radiotherapy, or brachytherapy.

Side effects of radiation therapy include fatigue, mild skin reactions, upset stomach, and loose stools.

Most side effects disappear soon after treatment ends.


Also called biological therapy, it is designed to stimulate the body’s natural defenses to fight cancer.

Use materials made by the body or in a laboratory to improve, target, or restore the function of the immune system.

Examples of immunotherapy include cancer vaccines, monoclonal antibodies, and interferons.

Remission and possibility of recurrence

A remission is when cancer can not be detected in the body without symptoms. This can also be termed “without evidence of disease.”

If cancer comes back after the original treatment, it is called recurrent cancer.

You can return to the same place (called a local recurrence), close (regional recurrence), or elsewhere (distant recurrence).

When this occurs, a test cycle will begin again to learn as much as possible about the recurrence.

After the test, the patient and their doctor will discuss the treatment options.

Often, the treatment plan will include the treatments described above, such as surgery, chemotherapy, and radiation therapy. However, they can be used in a different combination or administered at a different rate.

Your doctor may also suggest clinical trials that study new ways to treat this type of recurrent cancer.

Whichever treatment plan you choose, palliative care will be essential to alleviate symptoms and side effects.

If the treatment does not work

Recovery from cancer is not always possible. The disease can be called advanced or terminal if cancer can not be cured or controlled.

Patients with advanced cancer who are expected to live less than six months may wish to consider a type of palliative care called hospice care.

Hospice care is designed to provide the best quality of life possible for people nearing the end of life.

Hospice care is attendance at the end of life. A team of health professionals and volunteers provides it. They give medical, psychological, and spiritual support.

Caregivers try to control pain and other symptoms so that a person can remain as alert and comfortable as possible. Hospice programs also provide services to support a patient’s family.


Several measures that improve lifestyle can help reduce the risk of colorectal cancer:

  • Periodic screenings: those who have had colorectal cancer before, are over 50 years of age, who have a family history of this type of cancer, or who have Crohn’s disease should undergo periodic examinations.
  • Nutrition: Follow a diet with plenty of fiber, fruits, vegetables, and carbohydrates of good quality and a minimum of red and processed meats. Change from saturated to good quality fats, such as avocado, olive oil, fish oils, and nuts.
  • Exercise: Moderate and regular exercise has been shown to significantly impact a person’s risk of developing colorectal cancer.