Predictive value of relative changes in serum total sialic acid level for response to neoadjuvant chemotherapy in patients with locally advanced breast carcinoma

The aim of this study was to determine whether relative changes in total serum sialic acid (TSA) levels are associated with response to neoadjuvant chemotherapy in locally advanced breast carcinoma (LABC) patients. Forty-seven patients with stage III-B breast carcinoma and 20 healthy subjects (controls) were included to the study. TSA levels were determined in serum from patients at baseline and after completion of preoperative chemotherapy. Pathological responses to chemotherapy were determined on specimens of modified radical mastectomy underwent in responders. Association between the relative changes in serum TSA levels and the pathological response to chemotherapy was investigated. The baseline mean serum TSA level of LABC patients was 88.6+/-0.6 mg/dl and 66.9+/-0.7 mg/dl for the control group (p<0.0001). After 3 cycles chemotherapy, the serum levels of TSA were markedly decreased with pathological partial response (pPR) (73.8+/-1.0 mg/dl) and complete response (pCR) (68.1+/-1.9 mg/dl) compared to baseline values (p<0.05). In 8 non-responders, mean TSA value was 88.9+/-1.1 mg/dl (p=0.9 for pretreatment vs posttreatment TSA levels). Of 39 responders, 6 had pathological complete response (pCR) and remaining had pathological partial response (pPR). TSA levels derived from patients with pCR and from those with pPR were 68.1+/-1.9 mg/dl and 73.8+/-1.0 mg/dl, respectively (p=0.03). While TSA levels from pCR were not different from those of controls (p=0.4), there was a significant difference between TSA levels from pPR and from controls (p<0.0001). A significant correlation was demonstrated between the relative changes in TSA levels and pathological response (p<0.0001, coefficient of correlation [rs]=0.81). The ROC analysis showed that the discriminating ability was satisfactory and relative decrease by more than 21% in TSA levels indicated a pCR with the sensitivity by 83%, specificity by 76%. In conclusion, there is a significant correlation between the relative changes in TSA levels by chemotherapy and clinical/ pathological response to neoadjuvant chemotherapy in LABC patients.