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.
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. Overall, only 5% of adenomas progress to cancer, but your individual risk is hard to predict.
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).
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.
For the most part, it takes years for a polyp to become cancerous, and in fact most polyps never turn malignant. About one in four people develop adenomatous polyps by the age of 50, even though most of them will never develop colon cancer.
Most polyps grow slowly and take from between 10 and 15 years to become cancerous.
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.
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.
Figure 1 shows the cumulative incidence of colorectal cancer starting 1 year after a negative colonoscopy: 0.4% at 3 years, 0.8% at 5 years and 2.3% at 10 years. The overall incidence rate of colorectal cancer was 1.8/1,000 person-years in the study cohort.
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.
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.
If the cancer has not spread and is localized to the colon, then the 5-year survival rate is 91%. However, if the cancer has spread to the nearby tissues or lymph nodes, the 5-year survival rate is 72%. The survival rate drops to 14% if the cancer spreads to distant parts of the body.
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.
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.
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.
While the majority of colon cancers start as polyps, only 5-10% of all polyps will become cancerous.
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.
For patients with 1-2 sessile serrated polyps (SSPs) <10 mm in size completely removed at high-quality examination, repeat colonoscopy in 5-10 years. 12. For patients with traditional serrated adenomas (TSAs) completely removed at a high-quality examination, repeat colonoscopy in 3 years.
If a polyp is removed or a sample of the colon lining is removed (a colonic biopsy), it may take a few days (or more) to find out that cancer, an adenoma or another finding was discovered.
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.
; however, despite this effectiveness, it has also become evident that colonoscopy is not perfect and cancers occur after a “clear” colonoscopy at a rate of between 2.5% and 8.7% of the total cancers diagnosed, depending on the method used to calculate and the population.