About Colon Cancer

Early Detection

5 year relative survival for colorectal cancer by stage of tumor devopment (according to the American Cancer Society)

Stage 0 (cancer confined to polyp)	Virtually 100%
Stage I	93%
Stage II	80%
Stage III (Invades nearby Lymph Nodes)	55%
Stage IV (Invasion completely though colon wall and spread to distant organs)	8%

A note on the 5 year survival rate:
The overall survival of a particular individual diagnosed with cancer is measured in terms of the 5-year survival rate. The 5-year survival rate refers to the percentage of patients who live at least 5 years after their cancer is diagnosed. Many patients live far past the 5 year mark, and in general the 5-year survival rate is used to produce a standardized way of discussing prognosis. The 5-year survival rate does take into account patients who may die of other causes, such as heart disease or a stroke.

The 5-year relative survival rate is a slightly different and more accurate measure of survival, since it does not include patients dying of other diseases. The 5-year relative survival rate is displayed in the above table, and describes the prognosis for patients with colorectal cancer at a specific stage of diagnosis. The 5-year relative survival rate excludes patients dying of other diseases, and therefore is an accurate measure of deaths attributed solely to colorectal cancer.

Early Detection

Colorectal cancer can take many years to develop, which means that early detection greatly improves the chances of a cure. Screening for colorectal cancer is recommended in anyone age 50 years or older. Those younger than 50 should be screened if they are at increased risk. Increased risk is defined as one or more of the following factors.

Risk Factors

Age - the risk of developing colorectal cancer increases with age. At age 50 the risk of developing colon cancer and precancerous polyps increases dramatically.

Colorectal Polyps - polyps, especially adenomatous polyps are a major risk factor for colorectal cancer.

Personal History of Cancer - Individuals who have been diagnosed with and treated for colorectal cancer are risk for developing it in the future. Women who have had ovarian, uterine or cervical cancer are at a higher risk of developing colorectal cancer.

Family History of Cancer - Individuals whose immediate family has been previously diagnosed colorectal, ovarian, uterine, or breast cancer may have an increased risk of developing colorectal cancer, especially if the individual was diagnosed before age 55.

Chronic Inflammatory bowel disease such as ulcerative colitis and Chrohn's disease increases an individual's risk of developing colon cancer by as much as 30%.

Alcohol - heavy alcohol use is well recognized as increasing the risk of colorectal cancer.

Diet - diets high in saturated fats, red meat and refined carbohydrates may increase the risk of colorectal cancer. Diets low in fiber, fresh fruits and vegetables are associated with an increased risk of colorectal cancer.

Physical Inactivity - Individuals who are physically active are at a much lower risk of developing colorectal cancer

The Polyp to Cancer Pathway

The majority of colorectal cancer is caused by adenomatous polyps (adenomas) which may grow undetected in the colon. There are generally two factors that determine a polyp's chance of become cancerous: type and size. Even though there are several different types of colorectal polyps, most are generally considered benign. Adenomas however, are most likely to become cancerous if they grow undetected to a large enough size. Generally speaking, the larger a polyp grows, the more likely it is to become cancerous. After a polyp reaches approximately one inch in size, the risk of that polyp being malignant exceeds 20%. Thus it is extremely important to remove polyps no matter how small they are, in order to prevent their growth and progression to colon cancer.

Illustration courtesy of the National Cancer Institute

The diagram above illustrates the progression of polyp to a cancer and the cancer's subsequent progression if left untreated. The treatment of colorectal cancer and an individual's prognosis depends greatly on the stage of the tumor once it is discovered. Stage 0 represents the polyp stage where colorectal cancer is virtually 100% cured if the polyp is removed. If left untreated, the polyp can develop into a cancer which will grow and spread throughout the body. For early colorectal cancer in the stage I and early stage II phase, surgery may be all that is needed for successful treatment. However, if the tumor is in the stage III or stage IV phase of development, then more aggressive treatments with chemotherapy and radiation may be necessary.

The survival rates for individuals who are alive 5 years or more after being diagnosed with colorectal cancer depends on the stage of their disease at diagnosis.