Colorectal cancer is diagnosed after cancerous cells, often beginning as precancerous polyps, are found in the large intestine, or colon. These polyps can be tiny and cause no symptoms, so regular screening is suggested to remove polyps before they become cancerous.
Certain people may be at a greater risk for developing colorectal cancer, including those:
- Older than 50
- With a family history of colorectal cancer or polyps
- Who have genetic conditions that might make them more prone to having colon cancer
- Who have had other types of cancer
- Who have had ulcerative colitis or Crohn's disease
Cancer Now More Common in Young People
Aging increases a person's risk for developing cancer, but it is being diagnosed in people of all ages. In fact, cancers of the colon and rectum have been declining in older adults in recent decades and rising sharply in adults as young as 20.
Experts say people born in 1990 have double the risk of colon cancer and quadruple the risk of rectal cancer at, say, age 40, compared to someone born in 1950 at age 40. The American Cancer Society estimates about 13,500 new cases of colon and rectal cancers will be diagnosed in Americans under 50 this year.
Because doctors don't often consider this diagnosis in young adults, these patients may not get treatment until the disease has progressed.
Several reasons have been offered for this increase in colorectal cancers in younger adults, including rising obesity and poor diets. But a major factor appears to be genetics - a family history of cancer.
Higher Risks in Families with Cancer History
As many as one in five people who develop colorectal cancer have other family members who have had it.
"Risk is higher with a cancer family history, especially if the a relative was diagnosed with cancer when younger than 45 or if more than one relative was affected," said Morgan Dally, MS, CGC, LGC, Cancer Genetic Counselor at the Franciscan Health Cancer Center. "Precancerous polyps in a family member also is linked to higher risk."
Dangers of an Inherited Syndrome
The American Cancer Society reports that about 5 to 10 percent of cancers are hereditary, caused by underlying gene changes (mutations) that can cause family cancer syndromes. The most common inherited syndromes linked with colorectal cancers are familial adenomatous polyposis (or FAP) and Lynch syndrome, but other rarer syndromes also can increase colorectal cancer risk, according to Dally.
"Identifying families with these hereditary risks is important since colorectal cancer may develop early in these people and also may contribute to other types of cancer,” Dally said. “Early identification means doctors can recommend screening and other preventive measures before the cancer progresses."
Dally recommends that if you have a family history of polyps, colorectal cancer or an inherited syndrome, talk with your doctor about when you should begin screening. Also, if you personally have had polyps or colorectal cancer, please tell your close relatives so they can follow-up with their physicians.
You might also consider genetic testing to assess your cancer risk.
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