Colon Cancer Symptoms

Colon cancer is a type of cancer that begins in the colon or rectum, the two organs that make up the lower part of the intestine. Colon cancer symptoms are not clear immediately upon onset, and its symptoms may also resemble those of many digestive system diseases.

What Is Colon Cancer?

The wall of the colon and rectum is made up of several layers. Colorectal cancer begins in the inner layer (the mucosa) and can grow outward through some or all of the other layers. When the cancer cells are in the wall, they can then grow into the blood vessels or lymphatic vessels, and from there they can travel to nearby lymph nodes or to distant parts of the body.

Therefore, the stage or extent of the spread of colorectal cancer depends on how deeply it has grown into the wall and whether it has spread outside the colon or rectum.

Stages of Colon Cancer

It is important for the doctor to know the stage of the cancer to assess the condition and determine the best treatment plan. Stage 0 of colon cancer is the first and early stage of the disease, and stage four is the most advanced stage. Here is how the stages are determined:

• Stage 0: At this stage, the cancer cells are only in the inner lining of the colon and are known as carcinoma in situ.
• Stage one: The cancer has penetrated the lining or mucosa of the colon or rectum and may have grown into the muscle layer, but it has not spread to nearby lymph nodes or to other parts of the body.
• Stage two: The cancer has spread to the walls of the colon or rectum, or through the walls into adjacent tissues, but it has not affected the lymph nodes.
• Stage three: The cancer moves to the lymph nodes but not to other parts of the body.
• Stage four: The cancer has spread to other distant organs, such as the liver or lungs.

Early Colon Cancer Symptoms (Stages 0 to 2)

There may not be any clear signs or symptoms during the first stage of cancer. As the disease progresses, the symptoms may vary depending on the size of the tumor and its location in the large intestine.

The early symptoms may affect only the colon and lead to changes in bowel habits, and as the cancer grows, it may spread, resulting in systemic symptoms that affect the entire body.

If colorectal cancer in stages 0 to 2 causes symptoms, they may include the following:

• Sudden, unexplained weight loss.
• A change in stool consistency (loose or watery stool).
• Rectal bleeding.
• Blood in the stool (either in the form of bright red spots or dark, tar-like stool).
• A constant feeling of being unable to fully empty the bowels.
• Iron-deficiency anemia.
• Persistent abdominal pain.
• Gas.
• Diarrhea.
• Constipation.

Although these symptoms resemble symptoms of other less serious conditions, such as ulcers, hemorrhoids, Crohn's disease, and others, they should be discussed with the doctor. Blood in the stool should never be ignored, even if it appears intermittently.

Colon Cancer Symptoms in Stage 3

These are considered symptoms of the late stage of the disease, in which colon cancer symptoms appear more clearly.

In addition to the symptoms mentioned above, the symptoms may also include:

• Excessive fatigue.
• Unexplained weakness.
• Changes in stool that last more than a month.
• A feeling of bloating.
• Vomiting.

Symptoms of Metastatic Colorectal Cancer (Stage 4)

Patients with metastatic colorectal cancer may not always notice symptoms before diagnosis, and the symptoms of metastatic colorectal cancer may depend on the size of the tumor or tumors and where the cancer has spread outside the colon or rectum. For example:

• If the bones are affected, the symptoms may include fractures, bone pain, and/or elevated calcium levels.
• If the lungs are affected, the symptoms may include shortness of breath, difficulty breathing, coughing, pain, and fatigue.
• If the liver is affected, the symptoms may include nausea, fatigue, swelling of the feet and hands, increased abdominal girth, and jaundice (yellowing of the eyes and skin).
• If the lymph nodes in the abdomen are affected, this may lead to bloating and loss of appetite.
• If the brain and/or spinal cord is affected, the symptoms may include pain, confusion, memory loss, headache, blurred or double vision, difficulty speaking, and seizures.

Learn about: The Difference Between Appendicitis and Colon

How the Symptoms Are Diagnosed

If you have symptoms that may be caused by colorectal cancer or if examinations show something abnormal, the doctor will ask you to undergo further examinations to find out the cause.

Based on the symptoms you are experiencing, you will undergo a physical examination of the abdomen looking for masses or enlarged organs, for example a digital rectal examination (DRE); during this test, the doctor inserts a lubricated gloved finger into the rectum to feel for any abnormal lumps.

There are also some examinations that your doctor may wish to perform, such as:

• Colonoscopy: It is a test in which a thin tube with a light at its end is inserted through the anus into the rectum and colon to look closely inside. If any abnormal mass or growth (tumor) is found, a piece of it (a biopsy) can be taken and examined in the laboratory for cancer cells.
• Biopsy (sample): During a biopsy, the doctor takes a small piece of tissue where the cancer may be, then the tissue is examined for cancer cells. This is considered the best way to find out whether you have cancer.
• Computed tomography (CT) scan: A CT scan is similar to an X-ray, but the internal images are more detailed. This imaging can be used to help perform the biopsy accurately.
• Ultrasound: In this test, a small wand-like device is moved over the surface of the body to be imaged. This device emits sound waves and captures their bounce off the tissues. The echo is made into an image on the computer screen.
• Genetic tests: The cancer cells in the biopsy tissue can be tested for certain genes or proteins in the cancer cells such as BRAF, KRAS, MMR, and MSI. Knowing about these genes or proteins can help determine whether treatments such as targeted therapy or immunotherapy are the most appropriate in treatment.

Other tests can also be performed, such as MRI scans, X-rays, and blood tests, to look at the size of the cancer and whether it has spread.

Colon cancer symptoms and its treatment generally depend on the type of cancer, its size, and whether it has spread. Treatment may include surgery, radiation therapy, chemotherapy, targeted therapy, or immunotherapy, and many people receive more than one type of treatment.