It takes approximately 10 years for a small polyp to develop into cancer. Family history and genetics — Polyps and colon cancer tend to run in families, suggesting that genetic factors are important in their development.
Most polyps grow slowly and take from between 10 and 15 years to become cancerous. Due to this general time frame, most screenings are scheduled every 10 years which gives Colorectal Surgical Associates time to remove any polyps before they become cancerous.
Colon cancer, or cancer that begins in the lower part of the digestive tract, usually forms from a collection of benign (noncancerous) cells called an adenomatous polyp. Most of these polyps will not become malignant (cancerous), but some can slowly turn into cancer over the course of about 10-15 years.
Studies show that few smaller polyps are cancerous. As polyps slowly grow, however, the cancer risk rises. It's estimated that it takes about 10 years for cancer to form into a colorectal polyp.
Polyp Growth Rates
Cancerous polyps tend to grow slowly. It is estimated that the polyp dwell time, the time needed for a small adenoma to transform into a cancer, may be on average 10 years (17). Evidence from the heyday of barium enema examinations indicates that most polyps do not grow or grow very slowly (18).
Adenomas: Many colon polyps are the precancerous type, called adenomas. It can take seven to 10 or more years for an adenoma to evolve into cancer—if it ever does.
Surveillance refers to the process of evaluating patients with a personal history of polyps or cancer. People who have precancerous polyps completely removed should have a colonoscopy every 3-5 years, depending on the size and number of polyps found.
Once a colorectal polyp is completely removed, it rarely comes back. However, at least 30% of patients will develop new polyps after removal. For this reason, your physician will advise follow-up testing to look for new polyps. This is usually done 3 to 5 years after polyp removal.
It takes approximately 10 years for a small polyp to develop into cancer. Family history and genetics — Polyps and colon cancer tend to run in families, suggesting that genetic factors are important in their development.
How long does it take for a polyp to turn into cancer? The growth and mutation of colon polyps into cancer is a slow process, taking an estimated 10 years on average. So as long as patients are screened, it is unlikely they will develop cancerous polyps.
This means cancer and polyps can sometimes go undetected. So, despite having had a 'clear' colonoscopy, some patients go onto develop bowel cancer – referred to as post-colonoscopy colorectal cancer (PCCRC) or 'undetected cancer'.
Colon cancer is typically slow-growing, starting as a benign polyp that eventually becomes malignant. This process may occur over many years without producing any symptoms. Once colon cancer has developed, it may still be years before it is detected.
Colon cancers develop from precancerous polyps that grow larger and eventually transform into cancer. It is believed to take about 10 years for a small precancerous polyp to grow into cancer.
A threshold of ±20% change per year in polyp volume was chosen for the baseline categorization into the three groups, as this value is beyond the expected range of CT measurement error and should therefore constitute a real change. The baseline threshold for linear size change was set at ±1 mm per year.
Colorectal cancer can occur without polyps, but it is thought to be an uncommon event. Individuals with long-standing inflammatory bowel diseases, such as chronic ulcerative colitis and Crohn's colitis, are at increased risk for developing colorectal cancer that occurs in the absence of obvious polyps.
Symptoms and Causes
A polyp is the result of genetic changes in the cells of the colon lining that affect the normal cell life cycle. Many factors can increase the risk or rate of these changes. Factors are related to your diet, lifestyle, older age, gender and genetics or hereditary issues.
Not all polyps will turn into cancer, and it may take many years for a polyp to become cancerous. Anyone can develop colon and rectal polyps, but people with the following risk factors are more likely to do so: Age 45 years and older. A family history of polyps or colon cancer.
A gastroenterologist, the specialist who usually performs a colonoscopy, can't tell for certain if a colon polyp is precancerous or cancerous until it's removed and examined under a microscope.
Most colon polyps are harmless. But over time, some colon polyps can develop into colon cancer. Colon cancer can be fatal when found in its later stages. Anyone can develop colon polyps.
If your doctor finds one or two polyps less than 0.4 inch (1 centimeter) in diameter, he or she may recommend a repeat colonoscopy in 7 to 10 years, depending on your other risk factors for colon cancer. Your doctor will recommend another colonoscopy sooner if you have: More than two polyps.
More than one polyp or a polyp that is 1 cm or bigger places you at higher risk for colon cancer. Up to 50% of polyps greater than 2 cm (about the diameter of a nickel) are cancerous.
He says you might be surprised how often colonoscopies uncover polyps lurking in your colon. "Precancerous polyps are extremely common," he says. "We expect to find them in more than a quarter of the colonoscopies that we do at a minimum.
Under current guidelines, patients who have a colonoscopy with normal findings should get screened again in ten years.
Because colonoscopy testing is highly accurate and colorectal cancer tends to grow slowly, most experts recommend that people at average risk should have a baseline colonoscopy at age 50, then repeat the exam every 10 years.