Question 1. My father had cancer of the large intestine. It was treated. CEA level returned to normal. Does this mean that he is cured of the disease?
Response 1. There are some points to consider when evaluating a cancer patient’s response to treatment. The first of these is the stage when the disease is first diagnosed. Cancers are generally examined in four stages. As the number of stages increases, it is understood that the disease is more advanced at home. For example, when stage 1 is mentioned in large intestine cancers, it is understood that the tumor occupies a limited area in the intestinal wall. With the 2nd stage, it is meant to be explained that the tumor completely occupies the intestinal wall but has not spread to the surrounding lymph nodes. In stage 3, the cancer has gone to the lymph nodes around the intestine, but has metastasized far. For example, it has spread to the liver, lungs, bones, or brain.
Another factor that determines the course of a cancer patient is the degree of cancerization of the cells. What is meant by this is how different the cell is from the normal one. As the grade increases, the capacity of cells to divide and spread increases. Even if the response to drug therapy is good, the probability of recurrence of the disease increases.
Another factor that indicates the status of the disease in colon cancer is the tumor marker ‘carcinoembryonic antigen’ level that you mentioned. This antigen is known as CEA for short. In some studies, it has been shown that the higher the initial CEA level, the more difficult the treatment of the disease. However, this is not the absolute rule.
CEA is a protein found in the blood. It can be secreted from cancer cells as well as from normal cells. It can be elevated in some cancers other than bowel cancer, even in non-cancerous benign conditions. Therefore, it is not correct to use CEA for cancer screening in normal people. The correct thing is to check the CEA level after the diagnosis of colon cancer, and if the level is high, to check whether the blood level has decreased with the treatment. The normalization of CEA in a patient with a high initial CEA level indicates a good response to treatment. However, definitive evaluation should be made with imaging methods such as tomography, MR, PET.
Even if no tumor is seen in these imaging methods, it is necessary to know the pre-treatment status, including the initial stage, in order to be able to decide whether the disease will recur or not. Even in this case, rates can only be given in the light of statistical information. In stage 1, 5-year survival is over 90%. In Stage 2, this rate is between 75-85%. In stage 3, it varies between 40-80% depending on the condition of the disease. In the last stage, it is 8%.
