The clinical significance of serum soluble Fas and p53 protein in breast cancer patients: comparison with serum CA 15-3.

Serum sFas and p53 protein have been observed in breast cancer patients, but their clinical usefulness for diagnosis and therapy monitoring has not been clarified. The aim of this study was to compare the clinical utility of serum sFas and p53 protein with that of serum CA 15-3 as the most commonly used breast cancer tumor marker. Serum samples were taken from 35 normal healthy controls and 35 breast cancer patients before surgery, after 2 weeks of surgery and after six cycles of FAC chemotherapy. Serum sFas and p53 protein levels were measured using ELISA kits. Serum CA 15-3 levels were determined using IRMA kit. Mean Serum levels of sFas and CA 15-3 were significantly elevated while p53 protein was significantly declined in breast cancer patients than controls. Serum p53 protein showed the greatest significant area under the ROC curve (84.3%) followed by sFas (80.5%), then CA 15-3 (78%). The sensitivity, specificity and cut-off value for diagnosing breast cancer patients were 84.2%, 82.6% and 2.88 U/ml for p53 protein, 83.3%, 68.2% and 497.3 pg/ml for sFas and 45.8%, 100% and 23 U/ml for CA15-3. Surgical removal of breast resulted in a significant decline in serum sFas level with no effect on serum p53 protein and CA 15-3 levels. Six cycles of chemotherapy resulted in a significant elevation in serum sFas level with no effect on serum p53 protein and CA 15-3 levels. sFas was significantly correlated with tumor grade. It could be concluded that although serum p53 protein is superior to sFas and CA15-3 for diagnosis of breast cancer patients, only sFas is useful for monitoring the response of breast cancer patients to surgery and chemotherapy if the effect of systemic inflammatory reactions is excluded.