Medical professionals often refer to colorectal cancer, which includes colon cancer that affects the large intestine and rectal cancer that affects the lowermost part of the large intestine.
According to the American Cancer Society, 1 in 20 people are at risk of developing colorectal cancer during their lifetime.
The exact cause of colorectal or bowel cancer is not known. However, it is believed to develop when healthy cells become abnormal and start growing in number and accumulate in the lining of the colon, forming polyps. Left untreated, polyps may become cancerous.
Several factors increase your risk of developing colon and rectal cancer, including aging (above 50 years), some types of bowel diseases, family history, obesity, smoking, excessive alcohol intake, a sedentary lifestyle, Type 2 diabetes and regular intake of processed foods or red meats.
African-Americans are at a greater risk of colon cancer than people of other races.
As it can be difficult to treat colon cancer after it spreads to nearby areas, it is important to know what the early symptoms are. This can help you seek early treatment and give you a better chance in recovery.
Here are the important signs of colon cancer:
Constipation is an important sign of cancer in the colon. A 2011 study published in the Asian Pacific Journal of Cancer Prevention highlights the link between constipation and colorectal cancer risk.
An earlier 2004 study published in the European Journal of Cancer supported the hypothesis that constipation or laxative use increases the risk of colon cancer.
A tumor present at the far end of the colon can make it very difficult to eliminate waste products, thereby causing constipation.
If you persistently have fewer bowel movements per week, without any prior problem of constipation, consult your doctor to find out the exact cause.
If you suffer from diarrhea for more than a couple of weeks, it may be an early symptom of colon cancer.
When a tumor partially obstructs the bowel, it can cause alternating constipation and diarrhea due to leakage of liquid stool.
You may also experience frequent gas, abdominal pain, nausea and vomiting. Plus, a tumor may irritate or narrow the lining of the intestine.
It is important to consult your doctor when you have diarrhea that lasts more than a few days, as it can lead to dehydration, drain your body of nutrients and signal other serious problems, such as cancer.
3. Blood in Stools
Most often, blood in the stool is due to piles (hemorrhoids), where the veins in the back passage become fragile and cause a little bleeding during a bowel movement. This type of bleeding is generally red.
However, if you notice dark red or black blood in your stool, it can be a sign of cancer, such as bowel, rectal or colon cancer. It can also be due to a stomach ulcer.
Whether bleeding is due to piles, a stomach ulcer or cancer, it’s important to get it checked by a doctor. Proper diagnosis is essential for appropriate treatment.
4. Constant Feeling of a Bowel Movement
If you have a constant feeling of urgently needing to have a bowel movement or to strain but no stool is passed, it is not a good sign. This feeling can occur even after having a bowel movement.
Changes in your pattern of bowel movements can be a sign of colon cancer. It can occur when a tumor blocks the bowel and prevents you from completely emptying your bowels.
If you persistently have the sensation of incomplete evacuation after a bowel movement, discuss the problem with your doctor.
5. Narrow Stools
Thin, narrow stools are also a warning of possible colon cancer. A tumor present in the left side of the colon obstructs the passageway and often leads to narrow stools.
Do not delay discussing any change in your stools with your doctor. Diverticulitis and anal cancer can also cause narrowing of the stools.
6. Tender Abdomen or Abdominal Pain
If your abdomen, especially the lower part, hurts or feels tender when touched, this can be an early indication of tumor growth in the digestive tract, colon or rectum. In fact, abdominal pain is common in people who are later diagnosed with colon cancer.
A tumor can cause a block in the colon, restricting blood flow. This leads to abdominal pain that can be severe. This pain also can indicate that the cancer has begun to spread to other organs.
If abdominal pain or tenderness persists for more than 2 to 3 days, consult your doctor for proper diagnosis.
7. Unexplained Anemia
Anemia refers to a low red blood cell count in the body. The hemoglobin in red blood cells carries oxygen throughout the body.
Symptoms of anemia, such as pale skin, a fast or irregular heartbeat, shortness of breath, dizziness, and cold hands and feet, should not be taken lightly.
Unexplained anemia may be due to colon cancer. Typically, cancer in the right-side of the colon causes iron-deficiency anemia. This happens when tumors start bleeding slowly into the digestive tract, causing blood loss over time.
A 2008 study published in the British Journal of Cancer confirms a strong connection between anemia and cancer, with the risk rising as the hemoglobin level falls. This study also confirms iron deficiency as an independent predictor of cancer.
If you have signs of anemia, consult your doctor immediately to get your hemoglobin level checked.
8. Unexplained Weight Loss
If you are above the age of 50 and rapidly losing weight without any known reason, it is a cause for concern. Sudden, unexplained weight loss can indicate a serious health problem, including colon or rectal cancer.
A 2006 study published in the Annals of the Royal College of Surgeons of England found that unexplained weight loss happens mostly during advanced stages of colorectal cancers.
The growth of a tumor can lead to loss of appetite, as cancer can affect your metabolism, thus causing weight loss.
If you are rapidly losing weight without changing your diet or exercise routine, discuss this with your doctor.
9. Weakness and Fatigue
Another early symptom of colon cancer is fatigue, weakness and general malaise. Fatigue and tiredness after doing a laborious task is to be expected, but if you feel tired and weak most of the time, despite resting, do not take it lightly.
Large polyps or tumors in the colon can lead to iron-deficiency anemia that causes lower oxygen levels in the blood. This contributes to fatigue.
Fatigue and weakness can also be related to a number of chronic illnesses and medical disorders, sovisit your doctor to find outthe exact cause.
10. Gas and Bloating
Most people suffer from gas and bloating occasionally, but if the problem occurs along with some of the other symptoms mentioned here, it may be an indication of a tumor growing in the colon.
A tumor causes obstruction in the colon. Depending on the severity of the blockage, gas, solid and liquid may be prevented from passing out of the body. This in turn causes progressive bloating as well as gas.
If you have a lot of discomfort due to gas and bloating, see a doctor to rule out the possibility of cancer.
Tips to reduce your risk of colon cancer:
- Include a variety of fresh fruits, fresh vegetables and whole grains in your diet.
- Avoid drinking alcohol, or at least drink in moderation.
- Stop smoking and use of other tobacco products.
- Exercise for at least 30 to 40 minutes, 5 times a week.
- If you are overweight, take steps to lose weight gradually.
- Opt for regular screening tests to help prevent colon cancer.
Expert Answers (Q&A)
Answered by Dr. Peter S. Liang, MD (Gastroenterology)
What factors increase the risk of developing colon cancer?
There are many factors that increase the risk of colorectal cancer. Broadly speaking, we can categorize them into risk factors that you are born with (non-modifiable) and ones that you can change (modifiable). In terms of modifiable risk factors, obesity, sedentary behavior (spending hours sitting on the couch watching TV), and a diet high in red meat (especially processed meats such as bacon and sausage), all increase your risk.
Do any food items facilitate the growth of colon cancer tumor?
A diet high in red meat and processed (cured, smoked, salted) meats increase your risk of developing precancerous polyps and colorectal cancer.
What might suggest that colon cancer has spread to other organs?
There often aren’t any noticeable symptoms to indicate if colorectal cancer has metastasized or spread to adjoining organs. That’s because the tumors that spread to the other organ (such as the liver or lung) are usually smaller than the original (primary) colorectal tumor and often don’t cause pain, bleeding, or anything else you can feel.
It’s more common that the primary colorectal tumor will be accompanied by abdominal pain, bleeding, or anemia. It is really important to see your doctor if you experience any of these symptoms in order to detect potential cancer as soon as possible.
Are there any dietary recommendations for preventing colon cancer?
A diet high in fiber, vegetables, and fruits will lower your risk of colorectal cancer. In terms of animal protein, fish and poultry are better for you than red meat.
What is the major difference between a colon and colorectal cancer?
The colon is the large intestine, which is about 5 feet in length. The rectum is the last 5 inches of the colon. The risks for colon and rectal cancer are similar, so we usually talk about them together as colorectal cancer. However, the treatment for rectal cancer is different from colon cancer.
How fatal is colon cancer and what is its survival rate?
Overall, 5-year survival with colorectal cancer is 64%. But survival depends a lot on what stage it was diagnosed. Colorectal cancer that is detected early has a 5-year survival of 90%. However, if the condition has already metastasized at the time of diagnosis, 5-year survival is only 14%.
Therefore, if you’re 50 years or older, it is really important to get regularly screened for colorectal cancer. Screening not only helps us to find colorectal cancer at earlier stages, but it can also prevent cancer by detecting precancerous polyps that are surgically removable.
Is diverticulitis a symptom of colon cancer?
Diverticulitis is a painful inflammation/infection of small pothole-like outpouchings of the colon called diverticula. It is diagnosed based on a CT scan and can be treated with antibiotics. Although diverticulitis is a completely different condition than colorectal cancer, the two conditions can be difficult to tell apart because both can cause abdominal pain and inflammation seen on the CT scan.
Therefore, to make sure that you don’t have colorectal cancer that is mimicking diverticulitis, the recommendation is to undergo a colonoscopy at least 6 weeks after your symptoms have resolved.
Please enlighten our readers with some additional tips or inputs regarding colon cancer.
Colorectal cancer is the second leading cause of cancer death in the US, and 4-5% of people will be diagnosed during their lifetime. Besides adopting a healthy lifestyle which includes eating more fiber and vegetables, exercising, watching your weight, and eating less red/processed meat, it is really important to get screened.
If you are 50 years or older, please talk to your doctor about colorectal cancer screening. There are a number of different ways to get screened including colonoscopy and non-invasive stool tests. It’s best that you speak with your doctor about the various options, and make an informed decision about which test you prefer.
One-third of Americans are not up-to-date on screening, and this is something we need to change! By increasing screening rates, we can decrease the number of people who are diagnosed with and die from colorectal cancer. March is National Colorectal Cancer Awareness Month, so please talk with your doctor if you haven’t been screened already and tell your friends about the importance of this potentially life-saving screening test!
About Dr. Liang: He is an Instructor at the NYU School of Medicine and an attending gastroenterologist at the VA New York Harbor Health Care System, Manhattan Medical Center. Dr. Liang’s primary research interest is colorectal cancer prevention.
He studies sociodemographic and geographic disparities in colorectal cancer screening and outcomes, the comparative effectiveness of different screening strategies, and novel methods to increase screening adherence.