Breast cancer continues to be a major cause of death, despite the advances in the study of many prognostic factors. Although many prognostic factors have been studied, none reliably predict the response to treatment. This uncertainty in the prognostic factors could be overcome by defining the changes, occurring in patients at either the gene or protein level. Herein, attempts were made to examine the protein repertoire of patients using Proteomics.

Using conventional Proteomics, the high resolution 2-D electrophoresis followed by computational image analysis(Melanie program) and protein identification with mass spectrometry (MALDI-TOF), the serum of locally advanced breast cancer patients (stage III) was analyzed, and attempts were made to define the differences between recurred (or metastasis) patients ,and disease free patients of more than 4-years duration after surgery.

In the 2-D electrophoresis of serum, about 1,000 spots were gained in each gel, with the up and down expressed protein spots compared to the normal control protein map. Six of seven patients had Cytokeratin 9 in their peripheral blood. In the serum of recurred patients (one of two), no Haptoglobin-related proteins were detected. All five un-recurred patients had normal or elevated levl of serum Haptoglobin-related proteins.

The reduction of Haptoglobin-related proteins indicated the humoral immuno-depression in recurred patients. These findings may suggest the continuation of proper humoral immunity was important in the prevention of cancer recurrences or metastasis after surgery, especially in locally advanced breast cancer patients, which may suggests the value of immunotherapy in breast cancer patients to obtain good results.