This is a type of cancer that can affect the colon and rectum. It is important to find these cancers early. It is a common disease and is the second most common cause of cancer death in the United States.
Why does it happen?
It is thought that the risk of developing this type of cancer is related both to your genes and factors in the environment. There may be a link to dietary habits, but age is the major risk factor. Cancer of the colon is very uncommon before age 40, but there is a significant rise after this age. 90% of cases occur in people over age
50. Since the mid-1980s, death rates from colorectal cancer has been decreasing; this is thought to be related to better detection and removal of colon polyps, improved detection of cancer, and better treatments if cancer is found.
Risk factors for colorectal cancer include:
- A personal or family history of colorectal cancer or adenomatous polyps. Your family history is important. If a first-degree relative (parent, sibling, or child) has been affected, you have double the risk. If you have a personal history of polyps, the size, type, and number of polyps are important.
- A personal history of inflammatory bowel disease.
- Previous radiation to the abdomen.
- Possibly obesity, alcohol intake, heart disease, and cigarette smoking also increase risk.
Specific genetic conditions can increase the risk of colon cancer. 5% of colorectal cancer cases are due to specific genetic conditions. It is important to understand that the majority of cases of colorectal cancer occur in individuals who have no family history of colon cancer. The most common genetic syndromes are as follows:
- Lynch syndrome or hereditary nonpolyposis colon cancer (HNPCC). With this condition, a gene is mutated and there is increased risk of early-onset colon cancer. Other cancers are also more common with this condition.
- Familial adenomatous polyposis (FAP). In this condition, a gene (adenomatous polyposis coli) is mutated and multiple polyps of the colon occur in childhood and symptoms develop usually around 16 years old. If untreated, 90% of people will develop colon cancer by age 45.
What are the symptoms?
Often, people will have absolutely no symptoms. The development of symptoms is related to the size of the tumor as it grows, ultimately causing blockage or pressure on other organs.
Symptoms may include:
- Abdominal pain
- Change in bowel habits
- Blood in stool
- Weakness or tired feeling
- Anemia with low iron levels
- Black stools
- Weight loss
About 20% of patients will have metastatic disease (the cancer has spread outside the colon or rectum) at the time of diagnosis. The cancer can spread through the lymph system, bloodstream, or directly into nearby organs.
How is it diagnosed?
The majority of colon and rectal cancers arise from the tissue lining the GI tract.
Colonoscopy is the most accurate test to find this type of cancer. It can identify any lesions and tissue samples (biopsies) can be obtained.
Other methods of evaluation include:
- Air contrast barium enema
- Flexible sigmoidoscopy
- CT colonography
How is it treated?
Surgery to remove the cancer and some surrounding tissues is the main treatment. The lymph nodes, (tissue that filters the blood) will be examined to look for the spread of the cancer. Outcomes depend on how severe the disease was when first diagnosed. Chemotherapy (medicine to slow the growth of cancer cells) and radiation therapy (used to shrink the size of the tumor) may also be used in addition to surgery.
After being treated for cancer, you will be followed closely, to watch for recurrence of the disease. Blood work may be routinely performed including measuring a cancer tumor marker (CEA). In addition, repeat colonoscopies and CT scans may be ordered. If you have cancer of the colon or rectum, your first-degree family members, (parents, siblings, children) may be at increased risk of developing a similar type of cancer and should be screened.
What can I do?
Be sure to follow recommendations regarding screening for colorectal cancer. For further information regarding screening, please see the appropriate topic review.
Make sure you let your family members know about your medical history, as this can impact their risk.
There are studies that show certain things may be associated with a decreased risk of colorectal cancer such as:
- Regular physical activity
- A diet high in fruits, vegetables, and fiber while avoiding charred red meat and excessive amounts of alcohol may be protective.
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