Serum amyloid A: A new potential serum marker correlated with the stage of breast cancer

Abstract

Previous studies reported that serum amyloid A (SAA) is elevated in patients with tumors, including breast cancer, compared to healthy controls. In addition, the levels of SAA increase gradually with tumor progression. In this study, we investigated the blood SAA level of breast cancer patients, and evaluated its potential as a serum biomarker for the early diagnosis of breast cancer and as a staging estimate. SAA protein was determined by enzyme-linked immunosorbent assay in serum samples from 30 healthy women, 21 women with benign diseases and 118 breast cancer patients who were subdivided into 4 groups based on their clinical characteristics. SAA levels were not statistically different in stage I breast cancer patients compared with the healthy controls and benign breast disease patients. SAA concentrations had medians of 0.63 µg/ml in normal healthy women, 0.76 µg/ml in patients with benign disease (p>0.05) and 0.82 µg/ml in stage I breast cancer patients (p>0.05). By contrast, SAA values in stage Ⅱ, Ⅲ and Ⅳ patients had a significantly higher median compared to those of the healthy, benign breast diseases and stage I groups (p<0.05). Breast cancer patients with lymph node (LN) metastasis or distant metastasis were found to have significantly higher SAA concentrations than those without metastases. SAA is not a suitable marker for early breast cancer diagnosis, but its level is correlated with the stage of breast cancer. Thus, it may be a good candidate marker for the staging and prognosis of breast cancer.

Table I

Clinical characteristics of breast cancer patients analyzed for SAA concentration in blood by ELISA.

Figure 1

Concentrations of SAA in controls, benign breast disease and breast cancer patients at various stages of disease are shown. The Kruskal-Wallis test shows significant differences between the groups (p<0.05). Differences between certain groups are indicated by p-values calculated by the Mann-Whitney U-test. Spearman's rank correlation was used to check the correlation between SAA concentrations and the stage of breast cancer. SAA, serum amyloid A.

Figure 2

Concentrations of SAA in various lymph node metastasis grades of breast cancer are shown. The Kruskal-Wallis test shows significant differences between the groups (p<0.05). Differences between certain groups are indicated by p-values calculated by the Mann-Whitney U-test. SAA, serum amyloid A.

Figure 3

Concentrations of SAA in breast cancer patients with or without distant metastasis. Differences between certain groups are indicated by p-values calculated by the Mann-Whitney U-test (p<0.05). SAA, serum amyloid A.