Colon Cancer vs. IBS (Irritable Bowel Syndrome)

IBS and colon cancer may have some similar symptoms.

• Colon cancer occurs when abnormal cells grow and eventually spread through the colon wall to involve the adjacent lymph nodes and organs (metastasized).
• Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder.
• Colon cancer may have no symptoms until the disease progresses and becomes severe. When signs symptoms do occur, they may include bleeding from the rectum or bloody stools, or changes in bowel movement frequency. As the tumor grows, it can block the colon. Other symptoms of colon cancer may include:
  • Bloating
  • Abdominal pain
  • Nausea or vomiting
  • Weight loss
  • Changes in frequency or character of bowel movements
  • Constipation
  • Rectal pain
• Symptoms of IBS can vary, but usually include abdominal discomfort or pain. Other symptoms may include:
  • Abdominal cramping or pain that is relieved with bowel movements
  • Alternating periods of diarrhea and constipation
  • Changes in stool frequency or consistency
  • Gas
  • Bloating
  • Loss of appetite.
• Bloody stools and vomiting, are NOT signs of irritable bowel syndrome.
• Causes and risk factors for colon cancer include polyps, genetic abnormalities, ulcerative colitis (UC) or Crohn's disease (types of inflammatory bowel diseases), certain other cancers (breast, uterine, and ovarian), family history of colon cancer, obesity, smoking, and possibly diet.
• The cause of IBS is unknown, but it is thought to result from a combination of abnormal gastrointestinal (GI, digestive) tract movements, increased awareness of bodily functions, and miscommunication between the brain and the GI tract.
• Risk factors for IBS include abnormal movements of the colon and small intestines, hypersensitivity to gas pain, viral or bacterial infection of the stomach and intestines, small intestinal bacterial overgrowth (SIBO), or off-balance reproductive hormones or neurotransmitters.
• Call a doctor if you notice the following possible symptoms that may indicate colon cancer:
  • Bright red blood when you have a bowel movement
  • Change in the character or frequency of bowel movements
  • A sensation of incomplete evacuation after a bowel movement
  • Unexplained or persistent abdominal pain or distension
  • Unexplained weight loss
  • Unexplained or persistent nausea or vomiting.
• Seek immediate medical attention if you experience large amounts of bleeding from your rectum (especially if associated with sudden weakness or dizziness), unexplained severe pain in your belly or pelvis, or vomiting and inability to keep fluids down.
• If you have any symptoms of irritable bowel syndrome, or if you have IBS and experience unusual symptoms, call your doctor. Go to a hospital emergency department if problems are severe and/or come on suddenly.

Cancer is the transformation of normal cells. These transformed cells grow and multiply abnormally. Cancers are dangerous because of their uncontrolled growth and potential for spread. Cancer overwhelms healthy cells, tissues, and organs by taking their oxygen, nutrients, and space.

In colon cancer, these abnormal cells grow and eventually spread through the colon wall to involve the adjacent lymph nodes and organs. Ultimately, they spread (metastasized) to distant organs such as the liver, lungs, brain, and bones.

Most colon cancers are adenocarcinoma tumors that develop from the glands lining the colon's inner wall. These cancers, or malignant tumors, sometimes are referred to as colorectal cancer, reflecting the fact that the rectum, the end portion of the colon, also can be affected. Anatomic differences in the rectum as compared to the rest of the colon require that doctors separately recognize these areas.

Picture of Colon (Colorectal) Cancer

Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder.

IBS-C is irritable bowel syndrome with constipation. Symptoms most common with IBS-C include:

• Hard, lumpy stools
• Straining during bowel movements
• Infrequent stools

IBS-D is irritable bowel syndrome with diarrhea. Symptoms most common with IBS-D include:

• Sudden urges to have bowel movements
• Abdominal pain or discomfort
• Intestinal gas (flatulence)
• Loose stools
• Frequent stools
• Feeling of being unable to completely empty bowels
• Nausea

In the United States, one in 17 people will develop colorectal cancer. According to reports from the National Cancer Institute, colorectal cancer is the third most common cancer in U.S. men. Colorectal cancer is the second most common cancer in US women of Hispanic, American Indian/Alaska Native, or Asian/Pacific Islander ancestry, and the third most common cancer in white and African American women.

The overall incidence of colorectal cancer increased until 1985 and then began decreasing at an average rate of 5% per year in people 50 and older from 2009-2013 (available data). Deaths from colorectal cancer rank third after lung and prostate cancer for men and third after lung and breast cancer for women. Death statistics from colon cancer vs. rectal cancer is not clear as an estimated 40% of rectal cancers are misdiagnosed as colon cancer (another reason for lumping them together numerically).

IBS is not contagious, inherited, or cancerous. It occurs more often in women than in men, and the onset occurs before the age of 35 in about half of the cases. IBS occurs in 5% to 20% of children.

Colon Cancer Symptoms and Signs

Symptoms of colon cancer may not be present or be minimal and overlooked until it becomes more severe. Cancer screening tests for colon cancer thus are important in individuals 50 and older. Cancer of the colon and rectum can exhibit itself in several ways. If you have any of these symptoms, seek immediate medical help. You may notice bleeding from your rectum or blood mixed with your stool. It usually, but not always, can be detected through a fecal occult (hidden) blood test, in which samples of stool are submitted to a lab for detection of blood.

• People commonly attribute all rectal bleeding to hemorrhoids, thus preventing early diagnosis owing to lack of concern over "bleeding hemorrhoids." New onset of bright red blood in the stool always deserves an evaluation. Blood in the stool may be less evident, and is sometimes invisible, or causes a black or tarry stool.
• Rectal bleeding may be hidden and chronic and may only show up as an iron deficiency anemia.
• It may be associated with fatigue and pale skin due to the anemia.
• Changes in bowel movement frequency
• It usually, but not always, can be detected through a fecal occult (hidden) blood test, in which samples of stool are submitted to a lab for detection of blood.

If the tumor gets large enough, it may completely or partially block your colon. You may notice the following symptoms of bowel obstruction:

• Abdominal distension: Your belly sticks out more than it did before without weight gain.
• Abdominal pain: This is rare in colon cancer. One cause is tearing (perforation) of the bowel. Leaking of bowel contents into the pelvis can cause inflammation (peritonitis) and infection.
• Unexplained, persistent nausea or vomiting
• Unexplained weight loss
• Change in frequency or character of stool (bowel movements)
• Small-caliber (narrow) or ribbon-like stools
• Constipation
• Sensation of incomplete evacuation after a bowel movement
• Rectal pain: Pain rarely occurs with colon cancer and usually indicates a bulky tumor in the rectum that may invade surrounding tissue after moving through the colon's submucosa.

Studies suggest that the average duration of symptoms (from onset to diagnosis) is 14 weeks.

Irritable Bowel Syndrome Symptoms and Signs

IBS affects each person differently. The most common symptom of IBS in adults and children is abdominal discomfort or pain. Other common signs and symptoms include:

• Abdominal cramping and pain that are relieved with bowel movements
• Alternating periods of diarrhea and constipation
• Those who mostly have diarrhea as a symptom are considered to have IBS with diarrhea (IBS-D), characterized by sudden urges to have bowel movements, along with loose stools, , frequent stools, abdominal pain and discomfort, gas, and the feeling of being unable to completely empty the bowels. In severe cases of IBS-D, individuals may lose control of their bowels.
• Those who mostly have constipation as a symptom are considered to have IBS with constipation (IBS-C), characterized by passage of hard, lumpy stools, straining during bowel movements, and infrequent stools
• Change in the stool frequency or consistency
• Gassiness (flatulence)
• Passing mucus from the rectum
• Bloating
• Abdominal distension
• Loss of appetite

Indigestion affects up to 70% of people with IBS, however, it is not a symptom of IBS.

Signs and symptoms that are NOT IBS, but should still be brought to the attention of a health-care professional since they may be signs and symptoms of other conditions include:

• Blood in stools or urine
• Black or tarry stools
• Vomiting (rare, though may occasionally accompany nausea)
• Pain or diarrhea that interrupts sleep
• Fever
• Weight loss

Colon Cancer Causes and Risk Factors

Most colorectal cancers arise from adenomatous polyps. Such polyps are comprised of excess numbers of both normal and abnormal appearing cells in the glands covering the inner wall of the colon. Over time, these abnormal growths enlarge and ultimately degenerate to become adenocarcinomas.

People with certain genetic abnormalities develop what are known as familial adenomatous polyposis syndromes. Such people have a greater-than-normal risk of colorectal cancer. In these conditions, numerous adenomatous polyps develop in the colon, ultimately leading to colon cancer. There are specific genetic abnormalities found in the two main forms of familial adenomatous polyposis. The cancer usually occurs before age 40 years. Adenomatous polyposis syndromes tend to run in families. Such cases are referred to as familial adenomatous polyposis (FAP). Celecoxib (Celebrex) has been FDA approved for FAP. After six months, celecoxib reduced the mean number of rectal and colon polyps by 28% compared to placebo (sugar pill) 5%.

Another group of colon cancer syndromes, termed hereditary nonpolyposis colorectal cancer (HNPCC) syndromes, also runs in families (genetic, inherited). In these syndromes, colon cancer develops without the precursor polyps. HNPCC syndromes are associated with a genetic abnormality. This abnormality has been identified, and a test is available. People at risk can be identified through genetic screening. Once identified as carriers of the abnormal gene, these people require counseling and regular screening to detect precancerous and cancerous tumors. HNPCC syndromes are sometimes linked to tumors in other parts of the body.

Also at high risk for developing colon cancers are people with:

• Ulcerative colitis or Crohn's disease (inflammatory bowel diseases)
• Breast, uterine, or ovarian cancer now or in the past
• A family history of colon cancer

The risk of colon cancer increases two to three times for people with a first-degree relative (parent or sibling) with colon cancer. The risk increases more if you have more than one affected family member, especially if the cancer was diagnosed at a young age.

Other factors that may affect your risk of developing a colon cancer include:

• Diet: Whether diet plays a role in developing colon cancer remains under debate. The belief that a high-fiber, low-fat diet could help prevent colon cancer has been questioned. Studies do indicate that exercise and a diet rich in fruits and vegetables can help prevent colon cancer.
• Obesity: Obesity has been identified as a risk factor for colon cancer.
• Smoking: Cigarette smoking has been definitely linked to a higher risk for colon cancer.
• Drug effects: Recent studies have suggested postmenopausal hormone estrogen replacement therapy may reduce colorectal cancer risk by one-third. Patients with a certain gene that codes for high levels of a hormone called 15-PGDH may have their risk of colorectal cancer reduced by one-half with the use of aspirin.

Irritable Bowel Syndrome Causes and Risk Factors

The cause of irritable bowel syndrome is currently unknown. It is thought to result from a combination of abnormal gastrointestinal (GI) tract movements, increased awareness of bodily functions, and a disruption in the communication between the brain and the GI (digestive) tract.

Risk factors for IBS include:

• Abnormal (too fast or slow, or too strong) movements of the colon and small intestines
• Hypersensitivity to pain caused by gas or full bowels
• A viral or bacterial infection of the stomach and intestines (gastroenteritis)
• Small intestinal bacterial overgrowth (SIBO)
• Reproductive hormones or neurotransmitters may be off-balance in people with IBS.

Anxiety or depression may accompany IBS, though these have not been found to be a direct cause of IBS.

When to Call the Doctor for Colon Cancer Symptoms and Signs

Call your doctor or other healthcare professional if you have any of these signs and symptoms.

• Bright red blood on the toilet paper, in the toilet bowl, or in your stool when you have a bowel movement
• Change in the character or frequency of your bowel movements
• Sensation of incomplete evacuation after a bowel movement
• Unexplained or persistent abdominal pain or distension
• Unexplained weight loss
• Unexplained, persistent nausea or vomiting

Go to your nearest Emergency Department immediately if you have any of these symptoms.

• Large amounts of bleeding from your rectum, especially if associated with sudden weakness or dizziness
• Unexplained severe pain in your belly or pelvis (groin area)
• Vomiting and inability to keep fluids down

When to Call the Doctor for Irritable Bowel Syndrome Symptoms and Signs

If you have any of the symptoms of irritable bowel syndrome, or if you have IBS and experience unusual symptoms, call your doctor for consultation. Go to a hospital emergency department if problems are severe and/or come on suddenly.