Q: Dear Dr. Repici, are there screening tests that can help detect early stages of colorectal cancer? Best regards.
A: Screening for colorectal cancer is a fundamental method that is used to detect the disease early, usually before it causes symptoms. It is most common in a part of the population considered at risk for age or other characteristics, so as to identify a subset of individuals positive to the test, for the purpose of performing more and more sophisticated investigations. Typically, it allows us to identify a disease in pre-tumor stage (eg. Pre-cancerous polyps) or cancer in its earliest stages of development, so as to ensure timely therapeutic intervention. The screening tests commonly used are: – rectal examination: a digital examination of the rectum to detect the presence of any lumps or abnormal areas to the touch; – fecal occult blood test: a test that involves taking a stool sample, which is then analyzed in a laboratory, to detect any abnormalities in the blood. This method can not identify a large proportion of polyps and some cancers and it can give false positive results (ie suggest the presence of an abnormality when this is none present). When positive, however, it requires the execution of other procedures, such as colonoscopy. – Sigmoidoscopy or colonoscopy: tests that involve an endoscopic approach performed with instruments that are introduced rectally, pushed along the gut, and allow direct observation of lesions that may be present in the colon and rectum. – Double contrast barium enema: a method that is represented by an x-ray of the entire colon-rectum, performed after the patient has received a barium solution and air was introduced in the colon. With this type of examination, it is not possible to highlight the smallest diameter of polyps, to perform tissues samples or to remove polyps that may be eventually identified. The two main tests used in Italy, promoted both in different ways and dependent on the local and regional realities, are fecal occult blood test and colonoscopy.
