Variations in tumor marker levels in metastatic breast cancer patients according to tumor subtypes

Purpose: To investigate whether serum CA 15-3 and CEA levels show differences among subgroups of breast cancer patients at the time of diagnosis of early-stage disease and at disease relapse. Methods: Patients with metastatic breast cancer diagnosed from 2000 to 2010 were retrospectively analyzed. Data were obtained from medical charts. CA 15-3 and CEA levels of patients with metastatic disease at the time of diagnosis or who relapsed during follow-up were evaluated. Four different breast cancer subtypes were defined: estrogen receptor (ER) and/or progesterone receptor (PR) positive and HER-2 negative (luminal A), ER and/or PR positive and HER-2 positive (luminal B), ER and PR negative and HER-2 positive (HER-2 overexpressing) and triple negative (ER, PR and HER-2 negative). Fifty-eight (13.7%) of the patients were metastatic at the time of diagnosis. Results: 423 metastatic breast cancer patients were included. Of the patients, 232 (54.8%) had luminal A disease, 70 (16.5%) luminal B, 53 (12.5%) HER-2 overexpressing, and 68 (16.1%) triple negative disease. Preoperative CA 15-3 levels were raised in 48.1% of the luminal A group, in 42.8% of the luminal B group, in 26.0% of the HER-2 overex pressing group, and in 33.3% of the triple negative group. CA 15-3 levels after relapse were raised in 44.5% of the luminal A group, in 33.3% of the luminal B, in 28.9% of the HER-2 overexpressing, and in 38.8% of the triple negative group. Preoperative CEA levels were elevated in 44.3% of the luminal A group, in 28.5% of the luminal B, in 43.4% of the HER-2 overex pressing, and in 14.3% of the triple negative group. CEA levels after relapse were raised in 60.8%, 54.7%, 51.1%, and 36.0% of the patients in the 4 subgroups, respectively. Conclusion: This study showed that there are differences between the breast cancer subgroups in terms of tumor marker levels in metastatic breast cancer patients. Tumor marker elevation was lower in the triple negative group as compared to the luminal groups. Monitoring CEA levels in luminal A group may be beneficial in determining early relapses. However, this retrospective study requires further prospective confirmative cohort studies.