Written by:
Vladimir Comagic, MD
on
RT - digital rectal examination is the first examination, the simplest, cheapest, and falls in the domain of general practitioners. It is significant because it reveals tumors located in the final part of the colon, it can diagnose other, mainly benign disease in this region, which sometimes give similar symptoms. From all tumors of the rectum 2/3 of them are available for examination. And about 10% tumor of the entire colon is potentially accessible to digital rectal examination.
Unfortunately, about half of patients with gastrointestinal symptoms examined in General Practise does not have rectal exam done.
FOBT (faecal occult blood test) is the most commonly used test for the early detection of colorectal cancer because of its noninvasive nature, simplicity and low cost. Stool samples are taken in three consecutive days. Positive resukts for occult bleeding are when there is least 10 mg of hemoglobin in 1 gr of stool . The test requires preparation of patients for three days before testing, with so-called 'white diet' (taking of red meat, vitamin C, citrus fruits, iron supplements and anti-inflammatory non-steroidal drugs is prohibited). A positive finding does not confirm a diagnosis of cancer, but indicates the need for further testing.
Irrigography is a exam in which the contrast - barium, is inserted into the bowel through the rectal catheter and then x-rays scans are done. Scaning can be also done with dual-contrast ie. inserting barium and air, this method provides better accuracy. This method requires adequate preparation of the bowel. Its disadvantage is that a biopsy can not be preformed.
Flexible sigmoidoscopy is an endoscopic method that examine about 60 cm of the end of colon, two-thirds of cancers are located here.
Colonoscopy is the "gold standard" in diagnosis of colorectal cancer because beside the discovering of even the smallest changes - tumors, and taking biopsies there is a possibility of removing the polyps and therefore preventing their development into malignancy. It is an endoscopic method in which we are exploring the entire colon under the control of the eye. It requires bowel preparation ie. cleaning. Colonoscopy itself takes 20 to 45 minutes, is not painful, but for individual patients can be unpleasant.
Virtual colonoscopy is a new method that has not yet entered into routine use. It uses air as a contrast and recording is made by CT and MRI, it is providing additional information such as the spreading of the tumor mass to surrounding organs, presence of enlarged lymph nodes and presence of metastatic disease. Its sensitivity is very small for lesions less than 1 cm and lesions that are flat.
Endorectal ultrasound is an ultrasound examination using a probe which is incerted into the rectum. It evaluates tumor's stage, as well as the if there is if surrounding lymph nodes are affected . It is used in the diagnosis of tumors of the rectum.
Tumor markers -CEA and CA 19-9. It is a biochemical analysis of blood by which prove specific proteins. This markers are not strictly specific for colorectal cancer, since elevated values can be found with other malignant diseases such as breast, lung, stomach, as well as in patients with ulcers of the stomach and liver cirrhosis. CEA is increased in about 40% of patients with Colorectal Cancer. It's importance is in postoperative follow-up of patients, in terms of recurrence of the tumor after treatment.
Molecular biomarkers - free circulating DNA (CFDNA) in plasma, DNA from stool samples, this are diagnostic tests that are not in routine use as they are still expensive. Ultrasound, CT and MRI are used to detect local and systemic spreading of tumors (metastasis). Not a single test is perfect. Each has its advantages and disadvantages, and each reveals colon cancer at an early stage.
Irrigography is a exam in which the contrast - barium, is inserted into the bowel through the rectal catheter and then x-rays scans are done. Scaning can be also done with dual-contrast ie. inserting barium and air, this method provides better accuracy. This method requires adequate preparation of the bowel. Its disadvantage is that a biopsy can not be preformed.
Flexible sigmoidoscopy is an endoscopic method that examine about 60 cm of the end of colon, two-thirds of cancers are located here.
Colonoscopy is the "gold standard" in diagnosis of colorectal cancer because beside the discovering of even the smallest changes - tumors, and taking biopsies there is a possibility of removing the polyps and therefore preventing their development into malignancy. It is an endoscopic method in which we are exploring the entire colon under the control of the eye. It requires bowel preparation ie. cleaning. Colonoscopy itself takes 20 to 45 minutes, is not painful, but for individual patients can be unpleasant.
Virtual colonoscopy is a new method that has not yet entered into routine use. It uses air as a contrast and recording is made by CT and MRI, it is providing additional information such as the spreading of the tumor mass to surrounding organs, presence of enlarged lymph nodes and presence of metastatic disease. Its sensitivity is very small for lesions less than 1 cm and lesions that are flat.
Endorectal ultrasound is an ultrasound examination using a probe which is incerted into the rectum. It evaluates tumor's stage, as well as the if there is if surrounding lymph nodes are affected . It is used in the diagnosis of tumors of the rectum.
Tumor markers -CEA and CA 19-9. It is a biochemical analysis of blood by which prove specific proteins. This markers are not strictly specific for colorectal cancer, since elevated values can be found with other malignant diseases such as breast, lung, stomach, as well as in patients with ulcers of the stomach and liver cirrhosis. CEA is increased in about 40% of patients with Colorectal Cancer. It's importance is in postoperative follow-up of patients, in terms of recurrence of the tumor after treatment.
Molecular biomarkers - free circulating DNA (CFDNA) in plasma, DNA from stool samples, this are diagnostic tests that are not in routine use as they are still expensive. Ultrasound, CT and MRI are used to detect local and systemic spreading of tumors (metastasis). Not a single test is perfect. Each has its advantages and disadvantages, and each reveals colon cancer at an early stage.
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