Why are tumor markers present in low quantities within the normal range even if there is no cancer? Why aren't they 0? Can they be 0? To be sincere, I'm asking about
![Blood sample for cancer marker including CA 125, CA 15.3, CA 19.9, AFP and CEA test with laboratory report. Tumor marker test. 8931043 Stock Photo at Vecteezy Blood sample for cancer marker including CA 125, CA 15.3, CA 19.9, AFP and CEA test with laboratory report. Tumor marker test. 8931043 Stock Photo at Vecteezy](https://static.vecteezy.com/system/resources/previews/008/931/043/large_2x/blood-sample-for-cancer-marker-including-ca-125-ca-15-3-ca-19-9-afp-and-cea-test-with-laboratory-report-tumor-marker-test-photo.jpg)
Blood sample for cancer marker including CA 125, CA 15.3, CA 19.9, AFP and CEA test with laboratory report. Tumor marker test. 8931043 Stock Photo at Vecteezy
![Premium Photo | Blood sample for cancer marker test or tumor marker test with abnormal laboratory report Premium Photo | Blood sample for cancer marker test or tumor marker test with abnormal laboratory report](https://img.freepik.com/premium-photo/blood-sample-cancer-marker-test-tumor-marker-test-with-abnormal-laboratory-report_595440-1954.jpg)