Objectives: CA 15-3 and CEA are considered useful tumor markers in monitoring breast cancer patients. This study was undertaken to specifically evaluate the transient elevations in these markers that are observed during systemic treatment for metastatic disease. This phenomenon has been termed "spiking."
Design and materials: Serum tumor marker levels were investigated by enzyme immunoassay in 20 breast cancer patients without metastases and in 20 patients with bone metastases receiving systemic treatment.
Results: Both CEA and CA 15-3 levels were significantly elevated in the patients with bone metastases. Serum CEA and CA 15-3 levels in patients with metastases displayed a transient, but significant, elevation days 15 and 30, respectively, after commencing systemic treatment, which returned to pretreatment levels on the 60th day.
Conclusions: The spiking effect observed in the tumor marker levels should be carefully evaluated, and not be misdiagnosed as disease progression.