Step 1: Definition of Tumor Markers
Tumor markers are quantifiable substances, typically proteins, found in blood, urine, or bodily tissues, signaling the existence of specific cancers.
Step 2: Ovarian Cancer and CA-125
CA-125, a glycoprotein antigen, is elevated in approximately 80% of women diagnosed with epithelial ovarian cancer.
Its utility extends beyond initial diagnosis to encompass monitoring for cancer recurrence and assessing treatment efficacy.
Step 3: Evaluation of Options
- (A) CA 15-3: Primarily elevated in breast cancer, not typically associated with ovarian cancer.
- (B) CA-125: This is the correct marker, demonstrating a strong correlation with ovarian cancer.
- (C) CA 19-9: Often elevated in gastrointestinal and pancreatic cancers.
- (D) Protein S100 B: Associated with melanoma and tumors of the nervous system.
Step 4: Final Determination
The marker that is elevated in ovarian cancer patients is CA-125.