CT colonography is a relatively new noninvasive imaging technique that allows detection of colorectal polyps and cancers [1]. The sensitivity of CT colonography for colorectal polyp detection is directly related to polyp size [1]. Sensitivity for the detection of diminutive polyps (≤ 5 mm) is 10–67% [2–9].
Background: Prognosis of colorectal cancer (CRC) is greatly influenced by stage at diagnosis. Early colorectal cancer can be subtle on CT scans showing only mild wall thickening, small polyps, or subtle lymph nodes.
Most polyps are benign (not cancerous). Your doctor can tell if a colon polyp is cancerous during a colonoscopy by collecting tissue to biopsy. The results of the biopsy are typically sent to your doctor within a week. Only 5% to 10% of all polyps become cancerous.
The accuracy of detecting CRC in unprepared bowel on CT has been estimated to have an accuracy of 80% in one study [5] with sensitivities of 75%–100% and specificities of 86%–96% in other studies [6], [7], [8], [9].
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.
It may take up to 10 years for some polyps to become cancerous. Screening tests, including a colonoscopy, can help detect colon polyps.
Neoplastic polyps include adenomas and serrated types. Adenomas are the most likely to turn into cancer if given enough time to grow. Serrated polyps also may become cancerous, depending on their size and location. In general for neoplastic polyps, the larger the polyp, the greater the risk of cancer.
It's important to note that some cancers may be overlooked on a CT scan. Lesions may be missed for a variety of reasons, including location and human error. Still, CT is more sensitive than a simple X-ray. A CT scan can find lesions as small as 2-3 mm.
A traditional colonoscopy is the most widely known colorectal cancer screening procedure, but many patients are choosing a non-invasive CT (computerized tomography) Colonography instead. A CT Colonography doesn't require sedation and is just as accurate at detecting most precancerous polyps.
Colon cancer is undetected in 20% of abdominal CT examinations in patients subsequently proven to have colon cancer at colonoscopy.
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.
How Long Does It Take A Polyp To Become Cancerous? 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.
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.
Misinterpretation at CT colonography (CTC) can result in either a colorectal lesion being missed (false negative) or a false-positive diagnosis.
In patients with colorectal cancer, CT typically demonstrates a discrete soft-tissue mass that narrows the colonic lumen (,Figs 1, ,2). Large masses may undergo central necrosis and thus appear as a soft-tissue mass with central low attenuation or rarely air attenuation. This appearance may resemble that of an abscess.
1. Computed Tomography (CT) Scan. The doctor uses a CT scan to take images of the inside of your body from various angles using x-rays. Then, a computer combines the pictures into a three-dimensional, detailed image to reveal any tumors or abnormalities.
An upper endoscopy provides better detail than a CT scan or an upper gastrointestinal (GI) series, which uses X-rays.
Background. Computed tomography (CT) scans are commonly used to diagnose acute diverticulitis, but there are overlapping features between diverticulitis and colorectal cancer (CRC) on imaging studies. Hence, colonoscopy is typically recommended after an episode of acute diverticulitis to rule out underlying malignancy.
Colonoscopy revealed significantly more colon polyps and lesions than virtual colonoscopy (computed tomography, or CT scans) and standard air contrast barium enema X-rays, irrespective of polyp size, they found.
Some cancers, such as prostate cancer, uterine cancer, and certain liver cancers, are pretty much invisible or very hard to detect on a CT scan. Metastases to the bone and brain also show up better on an MRI.
While CT provides much more detail of damage and disease of internal organs, bones and blood vessels than some other imaging technologies, it can't show everything. Some types of cancer, for example, prostate cancer, uterine cancer and some liver cancers, may be harder to image using computed tomography.
Individuals who have had multiple CT scans before the age of 15 were found to have an increased risk of developing leukemia, brain tumors (6), and other cancers (7) in the decade following their first scan.
They can occur anywhere in the large intestine or rectum, but are more commonly found in the left colon, sigmoid colon, or rectum.
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).
Polyps are common in American adults, and while many colon polyps are harmless, over time, some polyps could develop into colon cancer. While the majority of colon cancers start as polyps, only 5-10% of all polyps will become cancerous.