Colon Cancer: Definition and Diagnosis
Cancer of the colon (often called colorectal cancer) occurs when cells behave abnormally and start to divide and multiply without order. When new cells are made, but not needed, a mass called a tumor is formed. Tumors that grow in the large intestine could be harmless (benign) and are called polyps that can be removed during a simple colonoscopy. Polyps left in the large intestine can become malignant tumors that contain cancerous cells. If these cancer cells leave the digestive tract, the cancer can spread to other areas (metastasis) and form new tumors.If metastasis occurs, a total cure of the cancer is not likely.
Colorectal cancer is difficult to diagnose because it’s various symptoms are not specific to the digestive system and include fatigue, weakness, difficulty breathing (shortness of breath), weightloss, stomach cramps or pain, and bloody stools. Other diseases, such as Irritable Bowel Syndrome, Crohn’s Disease or diverticulosis can also have these symptoms making diagnosis even more difficult.
To confirm diagnosis of colorectal cancer a colonoscopy or a barium enema is performed to localize the tumor.
How Does Colon Cancer Spread?
Colorectal cancers spread in three ways: through the blood, through the lymph system or through tissue. Cancer cells spread from the original tumor to another place in the body and form a new secondary tumor. No matter where else the cancer may spread, it’s still considered colon cancer. Therefore it’s possible to have colon cancer cells in other organs such as the lymph nodes or liver. That doesn’t mean that it’s liver cancer, it’s still treated as colon cancer. Doctors call the new tumor metastatic or distant cancer.
There are 5 stages of colorectal cancer that describe how far the disease has spread.
In Stage 0, abnormal cells are found in the inner layer of the colon wall. These cells aren’t cancerous yet and have not spread.
In Stage 1, cancer cells are found in the inner layer of the colon wall and may have spread to the muscle layer of the colon wall.
In Stage 2, cancer cells have spread to the muscle/outer layer of the colon wall and may be starting to spread to nearby organs.
In Stage 3, cancer has spread to at least 4 lymph nodes and one nearby organ.
In Stage 4, cancer has spread through the entire colon and into several lymph nodes and multiple organs.
Colon Cancer Prognosis
There are several factors that influence the outcome for someone diagnosed with colon cancer. The stage of the disease, age and the patient’s overall health all play an important role. A prognosis is only a prediction of a probable outcome based on collected data and isn’t a guarantee of a specific outcome. A patient is given a good chance of recovery if the cancer is likely to respond to treatment. Catching the disease early before it metastasizes is the best hope for a positive outcome - the earlier the cancer is diagnosed, the easier it is to treat. A research study published in the ANZ Journal of Surgery stated that patients diagnosed with Stage 1 colon cancer had a 91% survival rate after 5 years, while patients diagnosed at Stage 3 had a 59% survival rate over the same 5 year period.
Because the best chance for recovery happens with an early diagnosis, it’s important to have regular screenings if there is a family history of cancer, if you are over 50 (90% of colorectal cancer occurs in older people), have previous cancer diagnosis, diabetes, obseity or smoking.