The association of five preoperative serum tumor markers and pathological features in patients with breast cancer

Background The utility of frequently used serum tumor markers in breast cancer remains controversial. The study aimed to investigate the role of preoperative carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), cancer antigen 153 (CA153), cancer antigen 724 (CA724), and ferritin (FER) in the management of breast cancer and their relationships with pathological features. Methods A total of 804 patients with breast mass who underwent breast surgery and 305 healthy volunteers were enrolled. Preoperative serum levels of CEA, CA125, CA153, CA724, and FER were measured. And the pathological features of all the patients were recorded. The association of preoperative serum tumor markers and pathological features was analyzed. Results Among the 804 patients, 355 were identified as malignant cases and 449 as benign cases. CEA, CA153, and FER of patients with breast cancer were higher than those of healthy volunteer group and patients with benign breast diseases. The area under curve (AUC) of CEA, CA153, and FER for distinguishing patients with breast cancer and subjects with non‐breast cancer was 0.688 (95% CI: 0.656‐0.721), 0.609 (95% CI: 0.574‐0.645), and 0.623 (95% CI: 0.586‐0.660), respectively. CA153 correlated with tumor size, node status, and TNM stage, whereas CA125 with node status. No statistic differences of the five markers were observed among the four molecular subtypes. Conclusion Preoperative levels of CEA, CA153, and FER exhibit low diagnostic accuracy for breast cancer (stage I‐III). CA153 correlates with tumor burden, suggesting its prognostic value. The five serum markers do not correlate with molecular subtypes.

According to the expression of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2), and Ki-67, breast cancer is classified into four molecular subtypes, including Luminal A, Luminal B, HER-2-positive, and triple-negative. 2 As reported, Luminal A showed the best survival among the four subtypes, while triple-negative breast cancer showed the worst. 3,4 Therefore, molecular subtypes are important for individual treat- was more frequently observed in triple-negative patients compared with other three subtypes and they did not find any difference of serum CEA and CA153 among the four subtypes. 6,7 Thus, the limited knowledge of the relationship between serum tumor markers and the pathological features has obstructed the optimized use of serum tumor markers for patients with breast cancer.
Herein, we performed a retrospective study to compare preoperative serum levels of five tumor markers, including CEA, CA125, CA153, cancer antigen 724 (CA724), and ferritin (FER), among patients with breast cancer, patients with benign breast diseases, and healthy volunteers. Additionally, the diagnostic accuracy of the tumor markers for breast cancer was evaluated, and the association of preoperative serum markers with pathological features was analyzed to provide more evidence for clinical practice.

| Serum tumor markers and pathological features
Three milliliters of venous blood was collected from all patients before surgery. After centrifugation, serum CEA, CA125, CA153, and FER were measured using automatic chemiluminescence immunoassay system (SIEMENS ADVIA centaur; Siemens, Germany), and serum CA724 was measured using ROCHE E601 (Roche, Germany). Consensus. 2 And the TNM stage was evaluated by American Joint Committee on cancer (AJCC) staging system. 8

| Statistical analysis
All data were analyzed using SPSS 17.0 software (SPSS; Chicago, IL). The Mann-Whitney test was applied to analyze the differences between quantitative data for two independent groups and the Kruskal-Wallis test for three independent groups. Receiver operating characteristic curve (ROC) analysis was used to evaluate the diagnostic accuracy. If CEA was <0.5, 0.5 ng/mL was used for analysis instead. P < 0.05 was considered to be statistically significant.

| Preoperative serum levels of tumor markers
The preoperative serum levels of tumor markers in different groups are presented in Table 1. CEA, CA153, and FER of patients with breast cancer were higher than those of healthy volunteer group and patients with benign breast diseases (P < 0.05). In comparison with the healthy volunteer group, both patients with breast cancer and patients with benign breast diseases had higher CA125 (P < 0.05). However, there was no significant difference of CA724 among the three groups. In addition, the positive rates of tumor markers in three groups were calculated (as shown in Table 2).
To evaluate the diagnostic accuracy of CEA, CA153, and FER for breast cancer, ROC analyses were performed (as shown in Figure 1

| Serum markers and TNM stage
As shown in Table 3 and Figure 2, the preoperative serum level of CA153 had a rise trend along with the development of tumor. Among patients with breast cancer, the level of CA153 was associated with tumor size. Patients with (≧T3) had higher CA153 level than both patients with T2 and patients with T1, and patients with T2 had higher CA153 level than patients with T1. As to node status, the levels of CA153 were significantly elevated in both patients with N1 and patients with (≧N2) when compared to patients with N0 (P < 0.05).
Likewise, the levels of CA153 were significantly elevated in both stage II patients and stage III patients when compared to stage I patients (P < 0.05). Besides, a statistical difference of CA125 was found among the three groups of node status (P = 0.043).

| Serum markers and immunohistochemical results
As shown in Table 3, significantly elevated CEA and FER were found in PR-negative group when compared to PR-positive group (P < 0.05).
There were no statistical differences of the five markers between ERpositive group and ER-negative group, between HER-2-positive group and HER-2-negative group, and between Ki-67-positive group and Ki-67-negative group (P > 0.05). In addition, preoperative serum level of CA153, CA125, CA153, CA724, and FER showed no statistical differences among the four molecular subtypes (P > 0.05).   has been proposed to estimate prognosis and guide treatment.

| D ISCUSS I ON
Ki-67 is considered to be a proliferation index. Thus, molecular subtypes based on the results of ER, PR, HER-2, and Ki-67 are of great importance for clinicians. And to analyze the association of serum tumor markers with immunohistochemical results seemed to be meaningful. Unfortunately, we did not find any statistic differences of serum CEA, CA125, CA153, CA724, and FER among the four subtypes in the current study. In agreement with Fang's results, they found that CEA and CA153 did not correlate with molecular subtypes, but they found that CA125 exhibited statistical differences among various molecular subtypes, with the most frequent elevations occurring in the triple-negative tumors. 7 As for metastatic breast cancer, Geng et al 16 concluded that elevated CA 153 and CEA levels at initial diagnosis of recurrence were found to be associated with breast cancer molecular subtypes. In addition, Wu 6 and his colleagues reported that CEA levels were lower in patients with triple-negative breast cancer than patients with other subtypes, and CA153 did not correlate with molecular subtypes.
Thus, the association of serum tumor markers and molecular subtypes is not conclusive, and further studies with larger sample are needed. Additionally, our results showed both CEA and FER levels were greater in PR-negative group than in PR-positive group.  Consistent with Imamura's results, they also found the elevated CEA was more frequent in PR-negative group than PR-positive group. 17 There are some limitations should be acknowledged. First, as a retrospective study, the available data may have some biases.
Second, the level of tumor markers may be affected by several factors, such as age, region, body mass index, lifestyle, and environment.
Third, small sample size should be acknowledged. Nevertheless, this study contains a number of strengths. First, the inclusion and exclusion criteria were rigorous. Second, for the first time, five serum tumor markers prior to surgery were analyzed. Third, in despite of negative result, the study may be helpful in better understanding the association of the five serum markers with molecular subtypes.
In summary, our study indicated that preoperative serum levels of CEA, CA153, and FER were elevated in breast cancer patients, with low diagnostic accuracy for breast cancer (stage I-III). High preoperative CA153 may reflect tumor burden, suggesting that it can be used to predict prognosis of breast cancer patients and monitor advanced tumors. Additionally, there was no significant association of preoperative tumor marker levels with molecular subtypes. Therefore, further studies are needed to find out better tumor markers for the diagnosis and prognosis of breast cancer.

ACK N OWLED G M ENTS
None.

CO N FLI C T O F I NTE R E S T
None.