tumor marker
Measurable substance in blood, urine, or tissue that may indicate the presence of cancer or monitor treatment response.
Full Definition
A tumor marker is a biological molecule found in blood, urine, stool, or tissue that is produced either by cancer cells themselves or by the body in response to cancer. These markers can be proteins, hormones, enzymes, or other substances that are elevated in certain types of cancer. While tumor markers are valuable for monitoring treatment response, detecting cancer recurrence, and sometimes assessing prognosis, they are generally not specific enough to be used alone for cancer diagnosis or screening in the general population. Examples include PSA for prostate cancer, CA-125 for ovarian cancer, and CEA for colorectal cancer.
Usage
Usage note: Do not confuse with genetic markers (DNA variations) or inflammatory markers (indicators of inflammation). Tumor markers specifically relate to cancer detection or monitoring.
In Context
- "Serial tumor marker levels showed a declining trend, suggesting treatment effectiveness." — Oncology report
- "The tumor marker CA 19-9 was significantly elevated, consistent with pancreatic adenocarcinoma." — Laboratory interpretation