Just the Facts > Symptoms
What are the Symptoms of Colorectal Cancer?
Almost all cases of colorectal cancer begin with the development of benign or non-cancerous polyps. Polyps develop when cells lining the colon reproduce too quickly. These polyps can become cancerous, invading the colon wall and surrounding blood vessels and spreading to other parts of the body.
Many people with colorectal cancer experience no symptoms in the early stages of the disease. When symptoms appear, they will likely vary, depending on the cancer’s size and location in the large intestine. Studies suggest that the average duration of symptoms (from onset to diagnosis) is 14 weeks. There is no association between overall duration of symptoms and the stage of the tumor. Therefore, it is best to get regular screenings rather than rely on colon cancer symptoms to alert one to the presence of a tumor. This is because colon cancer can grow for years before causing any symptoms. But, knowing what to look out for most certainly cannot hurt.
This photo provides an illustration of the general anatomy of the colon, as well as an invading colonic tumor.
Symptoms of Colorectal Cancer May Include:
Constipation, having a bowel movement less than three times a week, can be your body’s way of suggesting that you make some minor adjustments in diet or exercise. However, constipation can also be a symptom of a colon cancer. In the beginning of the colon, waste material is slushy and can easily maneuver around anything that gets in its way. But as it nears the end of the colon, stool solidifies and is less forgiving of obstacles. A tumor in the rectum or far end of the colon can make it very difficult for waste to get by, thereby causing constipation.
Similarly, changes in bowel habits which include diarrhea for more than a couple of weeks may be a symptom of colon cancer and should be followed up with a visit to your family doctor. Make a conscious effort to know your bowel habits so you can recognize any changes.
Once stool is no longer in its slushy phase and begins to take shape, how it looks when it leaves the body can provide clues to what is going on inside. For example, small-caliber or ribbon-like stools can sometimes indicate that the waste squeezed by some sort of obstacle on its way out. In the case of colon or rectal cancer, that obstacle would be a tumor in the latter part of the colon or the rectum.
Sometimes a tumor causes a bowel obstruction, which is basically a road block in the colon. Depending on the severity of the blockage, solids, liquids, and even gas may be prevented from passing by. This leads to abdominal cramps that can be severe, especially if the blockage restricts blood flow to the colon. Painful cramps may also indicate that a tumor has perforated the bowel wall; bowel perforation is a medical emergency.
This is the most commonly experienced colon cancer symptom. As a tumor grows larger, the passage of feces can cause the tumor to bleed. It is common to see bright red blood if the tumor is near the anus or toward the end of the colon, but it is more common for the blood to be hidden inside the stools and dry if the tumor is in the first part of the colon or the right side. The blood may also be separate from the feces or you may see it on the toilet paper. Get into the habit of looking into the toilet before flushing.
*Unexplained Weight Loss/Loss of Appetite
An unexpected weight loss accompanied by other symptoms can indicate colon cancer. The pain and discomfort caused by a tumor can lead to loss of appetite, which in turn results in weight loss. The unexplained weight loss can be a sign that a tumor is releasing chemicals that are increasing one’s metabolism.
*Sense of Fullness
A tumor that grows toward the end of the colon or in the rectum may cause a sense of fullness. This is because your body senses that there is something else present by the exit. What it does not know is that it is a tumor and it is attached, so it isn’t going anywhere. It basically sees the tumor as a stubborn piece of waste, so you acquire that “I still have to go” sensation that cannot be relieved.
*Nausea & Vomiting
Nausea and vomiting can occur for a slew of reasons. In the minority of cases, nausea and vomiting can be symptoms of colon cancer. A large tumor present in the right side of the colon may prevent the digestive contents from moving forward and therefore cause back up of food, thereby causing nausea and possible vomiting to occur.
*Gas & Bloating
A pattern of gas and bloating may be an indication that a tumor is growing in the colon and occasionally causing a blockage. Even if the tumor isn’t large enough to cause a bowel obstruction on its own, stool may periodically become caught on the tumor while it is passing by, causing a temporary obstruction. While your bowel is blocked and air is trapped, you will be bloated. When the blockage resolves itself, all that air will need somewhere to go and you will be gassy.
Sometimes the presence of a tumor causes iron deficiency anemia, a condition that can cause you to feel extremely tired (lethargic). Tumors tend to bleed, which results in a loss of iron – an element that transports oxygen to your cells. This symptom is characteristic of tumors in the beginning of the colon. Since it is quite spacious in there, tumors can become fairly large and bleed quite a bit before causing any other colon cancer symptoms. The blood usually dries before leaving the body as well, which also allows the bleeding to go undetected.
Colon cancer can be present for several years before symptoms develop. Symptoms vary according to where in the large bowel the tumor is located. The right colon is spacious, and cancers of the right colon can grow to large sizes before they cause any abdominal symptoms. Typically, right-sided cancers cause iron deficiency anemia due to the slow loss of blood over a long period of time. Iron deficiency anemia causes fatigue, weakness and shortness of breath. The left colon is narrower than the right colon. Therefore, cancers of the left colon are more likely to cause partial or complete bowel obstruction. Cancers causing partial bowel obstruction can cause symptoms of constipation, narrowed stool, diarrhea, abdominal pains, cramps, and bloating. Bright red blood in the stool may also indicate a growth near the end of the left colon or rectum.
Though blood in your stool may be a sign of colorectal cancer, it can, however, indicate other conditions. Bright red blood you notice on bathroom tissue more commonly comes from hemorrhoids or minor tears (fissures) in your anus, for example. In addition, certain foods, such as beets or red licorice, can turn your stools red. Iron supplements and some anti-diarrhea medications may make stools black. Still, it’s best to have any sign of blood or change in your stools checked promptly by your doctor because it can be a sign or something more serious.