From the Research
CA 15-3 has a sensitivity of approximately 60-80% for detecting metastatic breast cancer, with the most recent and highest quality study suggesting a sensitivity of 49.4% in patients with distant metastatic disease 1. The sensitivity of CA 15-3 varies depending on the metastatic site, with higher sensitivity for liver and bone metastases compared to lung or local recurrences.
- CA 15-3 levels typically correlate with tumor burden, making it more sensitive in advanced disease than in early-stage breast cancer.
- False negatives can occur, particularly in patients with small volume metastatic disease or certain breast cancer subtypes.
- For optimal clinical utility, CA 15-3 should be used in conjunction with imaging studies and clinical assessment rather than as a standalone test.
- Serial measurements over time are more valuable than single determinations, as rising levels may indicate disease progression before it becomes clinically or radiologically apparent. The most recent study from 2013 1 found that the combination of CA 15-3 with other tumor markers, such as CEA and HER2, can enhance the sensitivity for detection of metastatic breast cancer.
- The study found that the combination of CA 15-3 and CEA had a sensitivity of 60.2%, while the combination of CA 15-3 and HER2 had a sensitivity of 57.8%.
- The study also found that the sensitivity of CA 15-3 was significantly better than HER2 in patients with tissue HER2- tumors. Overall, while CA 15-3 has limitations as a standalone test, it can be a useful tool in conjunction with other diagnostic methods for monitoring disease progression and treatment response in patients with metastatic breast cancer.