Tumor Marker Levels Elevate False-Positively in Postsurgical Breast Cancer Patients with High sGPT Levels or with Receiving Oral 5-FU or Its Derivatives.

BACKGROUND: False elevation of tumor marker levels (TM) has been encountered in some postsurgical breast cancer patients. METHODS: We investigated 33 postsurgical breast cancer patients whose TM (CEA, CA15-3, NCC-ST-439, or BCA225) measured every 3 months, showed elevation 3 times in a row in a 6-month period, and in whom metastases were not detected at theend of the 6-month period. Nine patients developed recurrence within 36 months of the end of the 6-month period and 24 patients did not develop recurrence for more than 36 months after the end of the 6-month period. RESULTS: Seven patients who stopped treatment with oral 5-FU or its derivatives because of severe nausea and appetite loss did not develop recurrence. Normalization of TM (CEA, NCC-ST-439, or BCA225) manifested within 3 months of the interruption of the medication. Six patients who showed simultaneous increase in serum glutamic-pyruvic transaminase (sGPT) and TM (CEA or BCA225) in the initial 6months did not develop recurrence. Three of 6 patients did not take any anti-cancer drugs. Correlation coefficiencies of sGPT with CEA in 4 patients were 0.467, 0.569, 0.738, and 0.910 and those of sGPT with BCA225 in 3 patients were 0.663, 0.826, and 0.840. CONCLUSION: A false-positive increase in CEA, NCC-ST-439 or BCA225 might be caused by treatment with oral 5-FU or its derivatives. CEA or BCA225 elevates false-positively in patients with high sGPT levels.