What is Colorectal Cancer?

Colorectal cancer, also referred to as bowel, colon, and rectal cancer is the medical term for any growth, tumor, or cancer of the large intestine or rectum. According to the World Health Organization and the Centers for Disease Control, colorectal cancer is second only to lung cancer as the most common form of cancer contracted.

The colon, or the large intestine, is the last organ that digested food passes through before it is expelled from the body. The colon stores feces, absorbing excess water and nutrients, passing it onto the rectum. In the rectum, waste is stored before defecation.

Any cancer can be life-threatening and terrifying; but with awareness and knowledge of the warning signs, screening, diagnosis, and treatment, you can prevent and detect colorectal cancer which important in overcoming any cancer in general.


Part of understanding colorectal cancer requires an explanation of how healthy cells function and what creates tumors and cancer. Cancer is a generalized term for a large group of diseases that all entail abnormal cell growth and lead in most cases to the formation of a mass or lump.

While in some cases, abnormal cell growth can lead to a relatively harmless and non-cancerous benign tumor, cancers tend to have six established traits or hallmarks.

These six hallmarks are growth without stimulation, resistance to growth preventing signals, avoidance of programmed cell death, unlimited replication potential, developing blood vessels, and invasion of other tissues.

Cancerous cells will stimulate their own growth as opposed to waiting for a signal to grow. Cells normally require a hormone or other molecular signal in order to begin the process of division. However, in cancer cells, these signals are not needed and cells will either generate their own signal or destroying the systems in place to prevent excessive growth or have altered proteins increasing growth within the tumor. Tumors will also resist signals intended to prevent or stop growth.

Normally cells have internal and external processes that halt division. These suppressor proteins usually activate when a cell is not ready to divide or if the cell’s DNA is damaged. Another method to prevent cell division in normal cells involves contact inhibitors. These send signals to the cell to stop dividing when they fill space and begin touching other cells. In cancer cells, these inhibitors are not there and therefore nothing limits their growth. Cells have the ability to destroy themselves, a process known as apoptosis.

This is a necessary process that is used to maintain body tissues or to remove damaged or infected cells. Cancerous cells do not have this ability, either by affecting the detection mechanisms, the signals to start apoptosis or the proteins involved all of these would prevent the elimination of cells. With apoptosis being one of the body’s best weapons against preventing the growth of tumors, the loss of this ability creates abnormal cells.

Along with apoptosis, normal cells do not divide indefinitely. Most cells have a limited number of divisions before they either are unable to divide again or die. This is from the DNA at the end of chromosomes known as telomeres that shorten after every division. When the DNA becomes too short cells stop dividing. Cancerous cells extend telomeres, circumventing the built-in ability to limit cell growth. Cancer cells can also accelerate the development of new blood vessels, ensuring a supply of oxygen and nutrients flowing to these cells. A growing tumor exploits the body processes to benefit and boost the growth of the tumor siphoning these things from the rest of the body.

The final trait of cancer is the biggest difference between harmless, or benign, tumors and dangerous and potentially fatal malignant tumors. When a tumor gains the ability to break away from its place of origin and spread throughout the body.

This is normally done by invading the bloodstream, surviving that hostile environment, and then exit the tissue to start dividing in the new tissue. Depending on its location, a tumor does not need to be malignant to be hazardous. Benign tumors on certain glands, organs, or tissue can have negative effects on the production of hormones, regulation of body processes, or just divert nutrients and oxygen from the rest of the body.

In the case of colorectal cancer, there is some danger to having a benign tumor as it could cause a blockage or digestive problems, but the real concern is with malignant tumors.

Colorectal cancer originating in the epithelial cells lining the gastrointestinal tract. Most often, the cells which mutate are the ones most involved in stem cell renewal and differentiation, overproducing them. If this is coupled with a breakdown in the proteins which monitor cell division and kill defective cells, the tissue affected the transition from a benign tumor to cancer.

Fortunately, in the last twenty-five years, the number of new cases and deaths from colon cancer has decreased significantly as more knowledge about the causes of colorectal cancer has to lead to preventing cases.

As well the death rate from colon cancer has gone down as advances have been made in detecting cancers earlier as well as in treating cancer.

Risk Factors

Like most other cancers, colorectal cancer has risk factors. Some of these risk factors can be changed, others are unavoidable. There are many lifestyle factors that increase your chances of colon cancer, most are related to diet and activity. The first of these risk factors is weight. The heavier a person, especially male, the greater the risk of developing colon cancer.

In general, there is a correlation between obesity and cancer risk. This in large part because heavier people tend to have lower insulin levels for multiple reasons. Also, obesity increases leptin levels, which tends to lead to the growth of colon cancer cells, although the science is somewhat unclear for the reasons for this. Somewhat along with bodyweight are dietary choices. There are a couple of different choices that can increase your risk of contracting colorectal cancer.

Primary of these are diets high in red or processed meats because of the higher strain they put on the entire digestive system. While it is uncertain at present, foods that are broiled, grilled, or fried tend to increase the risk of colon cancer. On the other hand, diets high in fruits, vegetables, and fibers (but not necessarily fiber supplements) tend to have a lower chance of contracting colon cancer. Some of this is attributed to the cleansing ability of these foods, although some of it might also be that these foods take the place of foods that show a clear rise in the risk of colorectal cancer.

Along with obesity, people who have type-2 diabetes, even after separating out other risk factors, have a higher chance of developing colorectal cancer. This is because diabetics produce more leptin and less insulin, although the exact reason this affects the tumors that become colon cancer is at this time still uncertain. Like with cancer in general, high consumption of alcohol and smoking tend to increase the risk of colon cancer. While moderate drinking, no more than two drinks for men and one for women, is possible without an increase in risk; any smoking can be hazardous and it is just good for your health to quit smoking.

The final voluntary factor that increases your risk for colon cancer is physical activity. The more sedentary your lifestyle, the more likely you are to contract colorectal cancer. Even just walking for twenty minutes a couple of times a week has been shown to lower your risk for cancer. Along with lifestyle factors, there are several other factors that increase your propensity for colorectal cancer like many other cancers.

The primary unavoidable factor that increases your chances of contracting colon cancer is age. While younger people do get colorectal cancer, the chances of being diagnosed increase dramatically after 50 and continue going up as people age. This is typical for cancer in general and is no different for colorectal cancer. Certain diseases and conditions also increase your risk of colon cancer.

If you have had colon cancer in the past, even if it entered remission, it is likely that you will develop cancers in other parts of the colon, especially if your first case was when you were a child or young adult. Other conditions that carry an increased risk are adenomas, inflammatory bowel disease, ulcerative colitis, and Crohn’s disease, mostly because of the stress this places on the lower intestines. This is especially true if adenomas are allowed to grow larger over time or inflammatory bowel disease goes untreated to the point of becoming dysplasia.

While dysplasia describes cells that look abnormal but are not truly cancerous, these dysplastic cells can change into cancerous cells. Other unavoidable factors that lead to a higher likelihood of colorectal cancer include a family history of colon cancer or polyps.

While some of this can be because of shared environmental factors, a larger reason is that there is a genetic disposition to many cancers, colon included, especially in cases when the diagnosis comes before 45. There are several genetic disorders that increase the chances of having colorectal cancer. Certain races and ethnicities tend to have high rates of colon cancer as well.

In the United States, African Americans have the highest rate of both diagnosis of and death from colorectal cancer. Globally, Jews of Eastern European descent have a higher rate. The reasons for this are still not understood entirely.


Most doctors recommend that you begin receiving regular yearly or bi-yearly screenings for colorectal cancer starting at the age of 50 when age factors begin accelerating your chances of contraction. If there are other factors or warning signs, it may be necessary to begin screenings earlier or more frequently. The most common screening test for colorectal cancer is high-sensitivity fecal occult blood tests (FOBT). Because both colon polyps and cancers can bleed, FOBT searches the stool of the patient for traces of blood. Samples are collected by the patient using a kit and returned to a doctor and the stool is tested for either hemoglobin levels or fecal immunochemical. The issue with using this test exclusively is that there are other factors that can generate blood in the stool including hemorrhoids or red meat consumption.

Even with these factors, if FOBT is done every two years, the death rate from colon cancer is reduced between 15 to 33% in patients aged 50 to 80 years.

A DNA test is starting to gain usage that is a multitarget test that not only looks for blood in the stool like an FOBT test, but it looks for several genetic markers common in colorectal cancer or precancerous adenomas. The DNA is shed by the cells lining the colon and collect in the stool as it is passed.

Unlike with FOBT, the sample collected by the kit is mailed to a laboratory for testing and the results analyzed with those testing positive for both the blood and the genetic markers to have a colonoscopy. This test proves better at detecting more cancers and adenomas, but that increased sensitivity tends to give a higher chance of false positives.

While more invasive, colonoscopy greatly reduces the risk of death from colon cancer because of its effectiveness in detecting cancers. This is because instead of checking for warning signs, a colonoscopy gives the doctor a visual either through a colonoscope, which is a flexible lighted tube that has a camera attached to allow an up-close view of the colon or a CT scan.

These tests require the entire colon to be cleansed of matter as well as the inflating of the colon to expand the colon and better allow for viewing. While the viewing is being done, any polyps or growths can be removed during the test.

Usually, because of the requirement of sedation and the invasiveness of the procedure, colonoscopies are recommended every ten years after 50 unless warning signs are seen in another testing. Another test that has gone out of vogue as technology has surpassed it is the double-contrast barium enema. This test was used before the development of the colonoscope.

In this test, the colon is filled with a barium solution, which outlines the colon when an x-ray image is taken. This test is rarely used because it is not as sensitive and accurate as a colonoscopy, usually only be done if the patient has complications that make a colonoscopy unfeasible.


Colorectal cancer manifests itself in several different ways within the bowels and this leads to various symptoms making diagnosing and discovering it difficult. This has to do with where cancer might be located and because of the functions of the lower intestine.

One of the clearest warning signs of potential for colon cancer is blood in the stool. This is because the tumor exposes more blood vessels to possible rupture as well as more surface area that can be broken. This blood in the stool or bleeding is usually the first clear warning sign that gets people to see their doctors and it is of utmost concern. Another symptom is a change in bowel movements.

This can just be as simple as its consistency and composition as stool could soften or harden because of the water absorption function of the intestine being affected. This can also become chronic diarrhea or constipation, especially if the tumor is closer to the rectum or grows larger. Doctors recommend that if you have a sustained change in bowel movement or any sustained irregularity for more than a month that you get screened for colorectal cancer. The potential for obstruction or occlusion of the colon that could create constipation also tends to give those with colon cancer the feeling that their bowels do not empty completely when they have a bowel movement.

Obviously, this is in part because there is something more in their colon than normal. But the tumor could affect flow enough to leave fecal matter in the large intestine or rectum. Potentially in conjunction with the aforementioned symptoms, there is often excessive pain, gas, and bloating. Much like with the other symptoms, it is clear why this occurs, especially as the growth becomes larger.

While regular gas and bloating might be caused by any number of conditions, but like with the other symptoms, if they are sustained for a few weeks, there is enough cause for concern that a doctor should be seen for testing. Like with other cancers, fatigue and weight loss are a sign of possible colon cancer.

While on its own these symptoms do not likely point to colorectal cancer, but because of the nature of cancer to divert resources from the rest of the body for its own growth these factors in conjunction with other symptoms that would point to colorectal cancer over other cancers. In general, because the symptoms themselves are variant and inconsistent, there is not a clear-cut way to self-diagnose colon cancer. Since it takes time for these symptoms to develop, it is rare to catch colorectal cancer early in its onset without regular screenings. But with several warning signs that are very concerning, a combination of symptoms usually gets those suffering from colorectal cancer once those symptoms are noticeable.

Stages and Treatment

Similar to other cancers, colorectal cancer has stages as it grows. How these stages manifest themselves in symptoms and danger and recovery rates are crucial to not only diagnosis but survival. In general, cancers have five main stages depending on how large it is and where it is located in the affected area, some of which can be broken down into sub-stages.

The first stage of colorectal cancer is referred to as stage 0. In this stage, the cancer cells are just in the mucous lining of the intestinal wall and the tumor is small. Because of their size and the small area affected, Stage 0 tumors can be removed when detected during a colonoscopy. If the tumor is in the later stages of Stage 0 colon cancer, removal of part of the colon or a colectomy may be necessary. Regardless, if detected this early, survival is highly likely. Because at this stage it is really only likely to be detected by invasive tests like a colonoscopy because of its small size and the rarity of it producing any outward symptoms, it is rare that colon cancer is treated in this stage.

Like with other cancers, ideally, you want to detect and treat cancer at an early stage, but outside of screenings because the patient is in a high-risk group, it is rare that colorectal cancer is diagnosed and treated at Stage 0. Once the cancer cells have begun to attach themselves to the muscular wall of the intestines or rectum, it has entered Stage 1. At this point, a patient might see some of the outward symptoms, but at this point, the growth might be small enough to not have a dramatic effect on the colon or the body as a whole.

Again, the cancerous cells are still likely small enough that they can be removed during a colonoscopy, but it is also more likely that at this stage that removal of the affected part of the colon or rectum is necessary. At this early stage, the affected area is small enough that the chances of survival are still high and the likelihood of treatment beyond the surgery is low.

Detection is more likely at this stage because there is a good chance that there are some outward symptoms that would get a person concerned enough to see their doctor. Once cancer has progressed through the wall of the intestine and into the tissue around the colon or rectum, Stage 2 colorectal cancer has begun. Because of the size of the growth at this point, it is likely that there are symptoms severe enough to be outwardly observable.

Depending on where the tumor has grown beyond the colon, there are sub-stages that do not have much effect beyond the path of treatment and what needs to be done in recovery. At this point, the affected part of the colon and surrounding tissue will have to be removed. Even though cancer has not spread to the lymph nodes around the affected area of the bowel will be removed and chemotherapy may be recommended to minimize recurrence. This is because there is a multitude of different complications that can occur like blockage of the colon, perforation of the intestinal wall, or cancer that appears abnormal when observed after removal.

Because of the aggressive treatment needed to ensure the removal of cancer at this stage, survival is more difficult but still likely. Still, if cancer is detected and treated at Stage 2, some doctors may not suggest chemotherapy because there is debate whether it reduces recurrence enough to justify the toll it takes on the body. With or without chemotherapy, the chance of successful recovery, as well as the risk of recurrence, is still high.

Unlike later stages of colorectal cancer though and the chances that cancer has spread to other parts of the body are low and the recurrences are mild enough that they can be caught and removed with colonoscopies. Once cancer has spread into the lymph nodes, cancer has entered Stage 3. At this point, the concern is greater as cancer becomes more aggressive, increasing the difficulty of treatment and lowering the recovery rate. Because cancer has entered the lymphatic system, it begins to affect how the body handles infection and illness as well as increases the chance of spreading. Because of the difficulty of eradicating cancer once it reaches the lymph nodes, on top of a colectomy and removing the affected lymph nodes, chemotherapy as well potentially as radiation treatment are undertaken.

Because of the physical toll that surgery presents at this stage, in patients who are older or in poor health, surgery may be bypassed and a routine of radiation or chemotherapy is performed alone. With or without surgery, at Stage 3, colorectal cancer has a lower rate of survival and as mentioned before, a higher risk of recurrence of tumors, requiring frequent screening.

A diagnosis of colorectal is rare in its early stages in large part because symptoms do not show up early and because the most effective screening tests are invasive enough that they are only done when other warning signs point to the potential of colorectal cancer. Stage 2 and 3 colorectal cancer still have a strong rate of survival, but colorectal cancer progresses quickly from Stage 2 and Stage 3 because of the proximity of lymph nodes to the bowels.

Once that cancer has spread to the lymph nodes, its spread quickens soon entering the bloodstream and spreading to other parts of the body. This is Stage 4 and is usually difficult to recover as it requires multiple surgeries and extensive chemotherapy and radiation treatments to eradicate cancer.

If cancer has metastasized extensively or the tumors are large attempts are made to shrink them with radiation or chemotherapy before the cancerous part of the colon is removed in either a colectomy or in more aggressive cases a colostomy, or cutting the colon above the affected part and removing the colon entirely. Because of the essential nature of the colon and the difficulty of recovering from any Stage 4 cancer, survival rates for Stage 4 colorectal are among the lowest of any cancers. Other factors like age and physical condition of the patient tend to contribute to lower the survival rate further.

Fortunately for all stages of colorectal cancer, many new drugs and treatments are being developed giving doctors many treatment options, potentially improving the chances of survival and recovery as well as limiting recurrence of colorectal cancer in the future.

Coping and Support

Coping with colorectal cancer can be difficult.

Not just because of treating the disease itself, but also because of the anxiety that can be brought on considering treatment decisions, the emotional concerns of both the patient and their loved ones, and the financial cost and other practical concerns.

Fortunately, most doctors, especially those who specialize in oncology, have been trained to help patients cope with their basic concerns and are versed in a wide variety of resources available to support colorectal cancer patients.

This can be as simple as the phone number for any of the many groups which are established to help with any number of different issues faced by cancer patients in general as well some geared towards the specific needs of colon cancer patients and their families or connecting the patient and their family with the various social services available through most hospitals. These groups are usually equipped and experienced in coping with colon cancer and the support needed not only during the treatment itself but in recovery.

Another important key to coping with any major medical condition, colorectal cancer included, is to communicate with doctors, therapists, and other support staff any concerns, problems, or complications as well as the necessary information being communicated back to the patient.

In general, the more that is known, the better both the doctor and the patient can successfully navigate what is always a difficult and taxing time. It is also important to remember that along with the physical toll cancer takes on the patient, there are emotional needs that the patient and those around them which need to be filled.

Emotional support may be just as important as the medical treatment and not only is personal therapy encouraged for the patient, but counseling and group therapy are recommended to help not only with coping with colorectal cancer, but giving a chance to commiserate with others who have been through similar situations.

Any cancer can be scary because of the connotation that it carries with it of not only the likelihood of death, at least the threat of a difficult ordeal on physical, emotional, and financial levels.

But with knowledge of what cancer, its diagnosis, and the treatment entail, that fear can be alleviated to some extent and a better chance of a full recovery is likely.

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