Signs of Colon Cancer

It is important for a person to recognize the signs of colon cancer early in the course of the disease so that prompt treatment is initiated. However, in many instances, there are no symptoms of colon cancer in the early stages or they are very non-specific. The signs of colon cancer are usually dependent on the site of the cancer.

Signs of Colon Cancer on Right Side

The bowel on the right side has a thicker lumen and is more spacious compared to the bowel on the left side. Therefore, bowel cancer of the right side grows to a large size before producing any noticeable symptoms. The most common sign of the right sided bowel cancer is:

  • Iron deficiency anemia: This symptom is a result of blood loss over a long period of time. Small amount of blood loss occurs from the tumor site, which gets mixed with the feces, and may be detected only on the chemical analysis of stools. This gradual loss of blood may lead to anemia which, in turn, may result in shortness of breath, weakness and lethargy. It is only when the tumor has grown to a big size that the loss of blood in stools is substantial leading to dark colored stools called as melena.

Signs of Colon Cancer on Left Side

The colon on the left side is narrower. Therefore, any abnormal growth on the left side may cause obstruction of the bowel. The signs on the left side include:

  • Change in bowel habits: The most noticeable signs of colon cancer of the left side include a distinct change in the bowel habits. The patient may experience days of constipation followed by bouts of diarrhea. The stools may become narrowed and string like, what in medical parlance is termed as “pencil stools.” The patient may complain of a sense of urgency or get a feeling of incomplete evacuation. There may be mucus in the stools.
  • Complete bowel obstruction: The cancer may grow so large that it may completely obstruct the bowel’s lumen. This may lead to severe pain in abdomen associated with vomiting.
  • Perforation: The cancer may erode the entire thickness of the bowel wall making a hole and causing a perforation. In such a scenario, the feces may leak into the abdominal cavity leading to symptoms of shock.
  • Rectal bleeding: A tumor in the lower part of the bowel or the rectum may bleed leading to blood tinged stools. In this case, the blood in the stools is often bright red in color and may be confused to be a symptom of hemorrhoids.

As the cancer increases in size, the patient may complain of other associated signs of colon cancer. The symptoms of bowel cancer in the late stage may include:

  • Severe pain in the lower abdomen.
  • A palpable lump in the lower abdomen.
  • Extreme fatigue.
  • Unexplained weight loss.
  • Bloating of the abdomen.
  • Heavy bleeding in the stools.
  • All the signs of the colon cancer in early stage like altered bowel habits, anemia, shortness of breath and weakness but much more exaggerated than before.
signs of colon cancer

Frequency and location of colon and rectal cancers. Courtesy John Hopkins Medicine

Other Signs of Colon Cancer

The symptoms of colon cancer are often confused with those of other diseases like irritable bowel syndrome, peptic ulcer disease, ulcerative colitis, Crohn’s disease and diverticulosis. Because of this confusion, valuable time is lost and the cancer is often diagnosed very late. It is important for the people to recognize the signs of colon cancer and they should meet their doctors as soon as they notice any of these signs. Although bowel cancer can strike at any age, people above the age of fifty are at a higher risk of developing this cancer. It has been noticed that while women are more likely to suffer from colon cancer, men are more predisposed to be afflicted by cancer of the rectum.

There are certain other factors which increase the likelihood of developing colorectal cancer. These include:

  • A family history of bowel cancer: The chances increase if either of the parents or any sibling has a history of colorectal cancer.
  • Personal history: Patients of breast, ovarian or uterine cancer are at an increased risk. A person who developed bowel cancer before the age of 60 is more likely to develop it a second time.
  • Diabetes: Patients suffering from diabetes have 30% to 40% more risk of developing this cancer.
  • History of adenomatous polyps: A patient with history of developing adenomatous polyps or a positive family history of familial adenomatous polyposis is at an increased risk of developing colon cancer.
  • Diet: People eating a diet poor in fibers are more likely to suffer from bowel cancer.

People who are at a higher risk of developing colon cancer are advised to go for regular colorectal screening tests. This is done to detect the disease at an early stage where it is easier to treat. These screening tests include colonoscopy, barium enema, sigmoidoscopy and CT colonography. Such people are also advised to go for regular fecal occult blood test to detect any blood loss in the stools. The importance of early recognition of the signs of colon cancer cannot be stressed enough.

Colon Cancer Treatment

Colon cancer treatment can vary depending on the extent of the spread of cancerous cells in an individual. There are six types of procedures adopted in the treatment for colon cancer. These are listed below:

  • Surgery
  • Targeted therapy
  • Radiofrequency ablation
  • Chemotherapy
  • Cryosurgery
  • Radiation therapy

Colon Cancer Treatment Procedures

1. Surgery:

Surgery is the most commonly used procedure for colon cancer treatment. It involves removal of cancerous tumor in an operation. Surgical removal of cancerous cells can be done for treating all stages of colorectal cancer. The different types of surgeries done for colorectal cancer treatment are described below:

  • Local excision: Local excision is typically done when cancer is detected at a very early stage. The procedure involves inserting a tube equipped with a cutting tool through the rectum to the colon. The cancer from the colon is then cut out through this tool without actually cutting the abdominal wall.
  • Resection of the colon with anastomosis: This procedure is typically adopted when the cancer is relatively larger. The procedure involves the removal of cancerous and some part of healthy tissue around it followed by the stitching together of the healthy parts of the colon.
  • Resection of the colon with colostomy: This process involves the removal of the cancerous cells and nearby healthy tissues. However, in this procedure, it is not possible to stitch together the healthy parts of the colon since a large part of the bowel is excised. Therefore, an opening or a stoma is made on the outside of the body through which waste can be passed out of the body with the help of a bag which is placed along the opening.

colon cancer treatment bowel resection
2. Radiofrequency ablation:

Another colon cancer treatment method involves the use of radiofrequency ablation. In this method, a special probe that is fitted with tiny electrodes is used for killing cancerous cells. This probe can be directly inserted though the skin by using local anesthesia and can also be inserted within the body by making an incision by using general anesthesia.

3. Chemotherapy:

Chemotherapy is often used in the treatment for colon cancer. This method involves the use of drugs for either killing cancerous cells or stopping their further proliferation.

Chemotherapy can either be systemic or regional. Systemic chemotherapy refers to the technique wherein drugs are either taken through the mouth or are injected into the veins. These drugs then make their way to the cancerous cells through the bloodstream. Regional chemotherapy involves administering the drugs directly in an organ, body cavity, or the cerebrospinal fluid.

4. Cryosurgery:

Another colorectal cancer treatment involves using an instrument for freezing and destroying abnormal cancerous cells. This technique is known as cryosurgery and it makes use of liquid nitrogen which has a temperature ranging between minus 346 and minus 320 degrees Fahrenheit for freezing the cancerous cells.

5. Radiation therapy:

Radiation therapy is another type of colon cancer treatment technique which makes use of high energy x-rays and radiation for either killing cancerous cells or stopping them from proliferating further.

Radiation therapy can by external or internal. In external radiation therapy, an external machine is used for directing radiation towards the cancerous cells. In internal radiation therapy, radioactive substances are injected inside the body near the cancerous cells. The radioactive substances can be sealed in catheters, needles, seeds, or wires.

6. Targeted therapy:

Targeted therapy is another common form of colon cancer treatment. This technique involves use of drugs and other substances for identifying and targeting only cancerous cells without causing any harm to the healthy tissues. There are two types of targeted therapies that are often used. One is the use of angiogenesis inhibitors and the other is the use of monoclonal antibodies.

Angiogenesis inhibitors act by blocking the growth of the blood vessels that are required for the proliferation of cancerous cells.

Monoclonal antibodies are typically given by infusion and have the capability of identifying proteins on cancer cells that promote their growth. These antibodies then target those proteins on the surface of the cancer cells and kill them or block their further growth.


Colon Cancer Treatment

Any of the above described treatments can be adopted depending on the stage of cancer. If a specific colon cancer treatment is found to be ineffective, then another one can be adopted.


Colon Cancer Stages

Colon cancer stages have been established to ascertain the extent to which colon cancer has spread in the body of an individual. Colorectal cancer staging is very important because it helps in devising an appropriate treatment plan and also provides a fair idea about the survival outlook. The different stages of this type of cancer, which doctors have described, are listed below:

  • Stage 0: Stage 0 is the first stage of colon cancer staging. At this stage, cancer is only limited to the inner lining (often known as the mucosa) of the colon. The stage 0 of colorectal cancer is also referred to as carcinoma in situ.
  • Stage I: This stage of bowel cancer is characterized by the spread of cancer to the second and third layers of the colon. By this stage, the cancerous cells spread to the submucosa and the muscle layers of the colon. It is important to note that at this stage, the cancerous cells do not spread beyond the outer wall of the colon. This implies that cancer is still limited to the colon/rectum area of the body.
  • Stage II: This stage is divided into three sub-stages namely, stage IIA, IIB, and IIC.
  1. In the stage IIA of the cancer, the cancerous cells spread from the muscle layer to the outermost layer (known as serosa) of the colon or the rectum wall.
  2. Stage IIB is characterized by the proliferation of the cancerous cells beyond the serosa but these cells have not impregnated the nearby organs of the individual.
  3. Stage IIC marks the proliferation of cancerous cells to the nearby organs of an individual as they move beyond the serosa.
  • Stage III: The stage III of colorectal cancer is further classified into stages IIIA, IIIB, and IIIC.
  1. Stage IIIA marks the spread of cancerous cells to at least one but less than four lymph nodes that are in the periphery of the colon or rectum serosa. This stage also marks the formation of cancer cells in the tissues surrounding the lymph nodes. The stage IIIA of colorectal cancer can also signify the proliferation of cancerous cells beyond the inner most layer (instead of the outermost layer) of the colon or the rectum. The cancerous cells can then spread to 4-6 lymph nodes in close vicinity of the colon.
  2. Stage IIIB is characterized by the proliferation of cancerous cells in 7 or more lymph nodes near the colon.
  3. Stage III C of bowel cancer represents the spread of cancerous cells to the nearby organs, or the formation of cancerous cells near the lymph nodes.
  • Stage IV: Stage IV of colorectal cancer signifies the spread of cancer cells to nearby lymph nodes or organs. With an advancement of this stage, cancerous cells might start forming in one or more organs that are not near the colon, for instance, the lungs, liver, or the ovary.

Determining colon cancer stages in an individual is critical for establishing the best treatment plan.

colorectal cancer stages

Image courtesy of Johns Hopkins Digestive Disorders Library

Identification of Colon Cancer Stages: Tests and Procedures

Colorectal cancer staging is primarily done to assess the extent of spread of cancerous cells. Colon cancer staging involves the use of specific tests and procedures. Some of these are listed below:

  • CT scan: Computed Tomography or the CAT scanning process involves injecting a dye in the body, taking pictures of various parts of the body through x-ray machines and then developing them through a computer linked to the x-ray machines.
  • MRI scan: MRI scan involves the use of magnetic and radio waves for taking pictures of the colon. At times, gadolinium is also injected in the veins so that cancerous cells can be observed clearly in the images.
  • PET scan: PET scans are also used for observing malignant tumor cells. This process involves injecting radioactive sugar in the body. Cancerous cells take up more sugar than the normal cells and appear brighter in the images.

Other procedures used for colon cancer stages include lymph node biopsy, chest x-ray, surgery, and carcinoembryonic antigen assay (CEA). Colon cancer stages, if identified correctly, can help the doctor in devising an appropriate action plan for targeting the cancerous cells.

Colon Cancer Stages: Image courtesy of Johns Hopkins

What is Colorectal Cancer?

Colorectal cancer can be described as a form of cancer that afflicts the colon or the rectum of an individual.  Cancer that starts forming in the colon is known as colon cancer whereas the one that starts forming in the rectum is known as rectal cancer.
Colorectal cancer affects the bowel region of an individual and is therefore, also referred to as bowel cancer.  Bowel cancer is often associated with a change in bowel habits and bleeding in an individual.
Colorectal Cancer

Colorectal Cancer Causes

Cancer is typically caused by an exponential increase in the number of cells, which are not required by the body. These additional cells grow up to form a mass of tissue often known as a tumor. The tumor might be harmless (benign) or cancerous (malignant). Cells from the malignant tumors often break away and spread to other parts of the body.

Rectal cancer and colon cancer typically start with the formation of a polyp (an abnormal growth) in the inner lining of the rectum or the colon.  A majority of these polyps can be benign though some of them have the tendency of becoming malignant. An early removal of these polyps can help in preventing bowel cancer.

Colorectal Cancer: Common Risk Factors

The exact causes are not known. However, various studies have helped identify the common risk factors for developing this form of cancer. These risk factors are listed below:

  • Age of 50 or more: Ageing increases your likelihood of developing bowel cancer. Almost 90% of the cases of this type of cancer are detected in people who are 50 years or more.
  • An occurrence of colorectal polyps: Some colorectal polyps, if left unattended, might become malignant. Therefore, it is best advised to find and remove polyps at the earliest.
  • Family history of bowel cancer: If your close relatives such as brothers, sisters, or parents have had this type of cancer at a young age, it increases your likelihood of developing bowel cancer.
  • Previous history of cancer: A person who has previously had this form of cancer has an increased likelihood of developing it a second time. Women who have had ovarian, uterine, or breast cancer are at a higher risk of developing bowel cancer.
  • Dietary habits: People who eat food that is rich in fat but low on fiber, calcium, and folate are also at a greater risk of developing bowel cancer.
  • Genetic modifications: Changes in genes also attribute to an increased risk for developing this cancer. Changes in the HNPCC gene or the APC gene can cause colorectal cancer.
  • Inflammatory Bowel Disease: People suffering from inflammatory bowel diseases like Ulcerative Colitis or Crohn’s disease are also at a higher risk of developing colorectal or bowel cancer.

In a vast majority of the cases, bowel cancer can be treated if detected at an early stage. Certain measures that can be taken to reduce your chances of developing bowel cancer include being aware of the symptoms and understanding the risk factors.

It is best advised to seek an appointment with your doctor if you observe any abnormal symptoms. The doctor might then advise bowel cancer screening if needed.

An increased rate of awareness about the symptoms and prompt screening has attributed towards a significant reduction in the number of deaths due to colorectal cancer.