|Clear benefit of screening for colorectal cancer.|
Colon, or colorectal, cancer is cancer that starts in the large intestine (colon) or the rectum (end of the colon). Other types of cancer can affect the colon. These include lymphoma, carcinoid tumors, melanoma, and sarcomas. These are rare. In this article, colon cancer refers to colon carcinoma only.
In many cases, colon cancer is treatable when caught early, making screening important. When treated at an early stage, many patients survive at least 5 years after diagnosis. Stages I, II, and III cancers are considered possibly curable. In most cases, stage IV cancer is not considered curable, although there are exceptions.
Now researchers report at the ESMO 2014 Congress in Madrid, that the introduction of biennial colorectal cancer screening in a region of France increased the rate of diagnosis of high risk pre-cancerous polyps by 89%. The researchers studied the region of Côte-d'Or, where a registry has been collecting data on adenomas since 1976. They wanted to evaluate the rate of diagnosis of adenomas before and after the initiation of a screening program using fecal occult blood testing that began in 2003.
The study included all residents aged between 50 and 74 years of age who had a first adenoma identified between January 1997 and December 2008. The researchers showed that 38.7% of these people had high-risk adenomas, meaning they were larger than 1 centimetre in diameter, involved the finger-like projections called villi in the intestinal lining, or exhibited a high grade of dysplasia.
For such high-risk adenomas, age-standardized diagnosis rates were 136 per 100,000 people before screening program and 257 per 100,000 after, which correlates to a percentage increase of 89%. The corresponding rates for non-advanced adenomas were 235 and 392 diagnoses per 100,000, with a percentage increase of 68%.
The researchers also found that the rate of detection did not continue increasing between the 2005 and 2007 rounds of screening. However, they suggest that shifting the methodology used in the screening programs from the more common guaiac test to immunochemical testing will improve results in the future.
Many retrospective and prospective studies have demonstrated the value of screening for adenoma, polyps and manifest colorectal cancer with respect to early diagnosis and treatment. However, the best method to use is not clear. The optimal method for increasing the detection rate for high risk population is colonoscopy, or at least sigmoidoscopy, which is implemented as standard in Germany and in the US.