Tumor Markers

Key Information

Monitoring levels of tumor and indicating a recurrence

CEA (Carcinoembryonic Antigen) (Stomach)

Persistent elevated levels indicate residual or recurrent metastatic carcinoma; nonspecific to stomach cancer

CA 19-9 (Cancer Antigen 19-9) (Stomach)

Monitors post-therapeutic gastrointestinal cancer for recurrence; nonspecific to stomach cancer

CA 195 (Cancer Antigen 195) (Stomach)

Detects gastrointestinal cancers; changing level indicates progression or regression of tumor load; nonspecific to stomach cancer

SCC (Squamous Cell Carcinoma Antigen) (Esophagus)

Monitors tumor burden after treatment for squamous cell carcinoma; used in advanced cases; squamous cell specific

5-HIAA (5-Hydroxy-Indol Acetic Acid) (Small intestine)

Quantitative analysis of urine levels; levels above 15 mg/24 hours indicate malignant carcinoid tumors (argentaffinomas), which may also appear in stomach, appendix, or lower intestine

Go to the Tumor Markers page of the Diagnostic Tests module for more information.


Suggested Citation

SEER Training Modules: Tumor Markers. U.S. National Institutes of Health, National Cancer Institute. Cited 21 December 2025. Available from: https://training.seer.cancer.gov.