(rÄâ²dÃ¤r) 1. A method of detecting distant objects and determining their position, speed, or other characteristics by causing radio waves to be reflected from them and analyzing the reflected waves. The waves can be converted into images, as for use on weather maps.
A high level of the marker may indicate a worsened prognosis in some situations. The most effective and common purpose of tumor markers is to monitor the cancer treatment. As the cancer levels go on decreasing in the body, the marker also goes down. If the marker remains stagnant or increases, it is usually an indication that the patient is not responding sufficiently to the treatment.
1 The tumor marker tests check for two substances in the blood that colorectal cancer may produce: carcinoembryonic antigen (CEA) and CA 19-9. 2  The tests can help determine the effectiveness of treatment and, sometimes, disease recurrence.