Iran is a high incidence area of esophageal cancer (Ghavamzadeh
et al., 2001). The majority of Iranian patients have been reported
from the north and northeast regions of the country (Ghavamzadeh
et al., 2001). Squamous cell carcinoma is the most common pathologic
diagnoses with esophageal malignancy (Ghavamzadeh et al.,
2001). Several potential tumor markers have been suggested for esophageal
squamous cell carcinoma. Preoperative serum Squamous Cell Carcinoma Antigen
(SCCAg) levels in squamous cell carcinoma of cervix and lung are usually accompanied
by higher stage and poorer prognosis (Bae et al.,
1997; Body et al., 1990; Hatzakis
et al., 2002; Kornafel and Wawrzkiewicz, 1989)
but its prognostic significance in esophageal carcinoma is still under investigation.
According to high prevalence of esophageal carcinoma in our region, this study aimed at evaluation of serum levels of this antigen in esophageal squamous cell carcinoma and correlation of its levels with clinicopathologic characteristics of patients. Up to now, such study has not been performed in Iran.
MATERIALS AND METHODS
Forty six patients with a biopsy-proven diagnosis of esophageal squamous
cell carcinoma were recruited to this study. They consisted of 16 males and
30 females (mean age, 61.21 years; median, 58; range, 40-90) referred to oncology
departments of Ghaem and Omid hospitals of Mashhad University of Medical Sciences
(Mashhad, Iran) between 2005 and 2007. All cases had not undergone radiotherapy,
chemotherapy and surgery and had not any sign or symptom of primary squamous
cell carcinoma in other parts of the body.
The locations of tumors were determined by endoscopy. In 39 patients, it was
located 16 to 40 cm from the incisor teeth (mean, 27.06; median, 28.5) of which
30 (76.9%) and 9 (23.1%) cases had tumor in the middle and distal third of esophagus,
The lesion length of 34 patients was reportable according to the radiological view or endoscopic report with the mean of 7.25 cm (median, 7.5; range, 3-13.5).
The lesions were histologically graded. Clinical staging was based on TNM staging using a combination of radiologic, clinical and postoperative findings (Table 1).
Patients samples which had been taken before treatment were assayed for
SCCAg levels in reference laboratory based upon the direct sandwich RIAs using
CanAg SCC EIA kit (Fujirebio Diagnostics AB, Sweden).
Samples were incubated with biotinylated Anti-SCC monoclional antibody for 1 h. After 4 times washing, Chromogen reagent was added to each well and the enzyme reaction was allowed to progress. During the enzyme reaction a blue color developed if antigen was present. The intensity of the color was proportional to the amount of SCCAg present in the samples.
After 5 min, the enzyme reaction could be stopped by HCl solution. The color
intensity was determined by spectrophotometer at 620 nm (or at 405 nm after
addition of stop solution). The SCCAg concentrations of samples were then read
from the standard curve (Fig. 1).
|| Clinicopathologic factors of patients with esophageal squamous
|| The standard curve of SCCAg concentrations
According to manufacturer instruction, CanAg SCC calibrator values should be assigned regarding a set of in-house reference standards. So, in present study, SCCAg concentration of more than 3 ng mL-1 was considered as positive.
Data were analyzed using descriptive indexes and analytical tests including
Chi-square, t-student and Mann-Whitney.
RESULTS AND DISCUSSION
The mean pre-treatment SCCAg level was 3.82 ng mL-1 (median, 0.8; range 0.1-87) and just 10 patients (21.7%) had the elevated rate of SCCAg.
Two of 8 patients (25%) aged 50 years and under had positive SCCAg levels,
roughly the same as 8 of 38 (21%) in those aged over 50 at diagnosis. The positive
rate of SCCAg was 37.5% (6 of 16) in males and just 13.3% (4 of 30) in females
Three of 13 patients (23.1%) with grade I tumor had positive rates of SCCAg
compared to 3 of 11 (27.3%) and 3 of 15 (20%) in those with grade II and
III, respectively (Table 2).
Patients with stage IV disease had the highest percentage of SCCAg positive serum (6 of 10, 60%) while the figures in cases with stage I and II were 2 of 6 (33.3%) and 2 of 12 (16.7%), respectively. It was only 2 of 18 (11.1%) in patients with stage III.
Tumor size was the only studied clinicopathologic factor significantly associated with SCCAg. The mean tumor size for SCCAg positive patients was 8.8±1.89 cm (median, 9.5; range, 5-11) in contrast to 6.99±2.21 cm (median, 7; range, 3-14) for the SCCAg negative ones (p = 0.031).
In present study, 21.7% of patients with esophageal squamous cell carcinoma
had positive rate of SCCAg according to the cut-off point of 3 ng mL-1.
But most similar studies have used lower cut-off level. With cut-off point of
2.5 ng mL-1, Molina et al. (1990)
have detected this marker in 57.7% of patients suffered from squamous cell carcinoma
of various organs. Even the cut-off point has been set at 1.5 ng mL-1
in some studies (Kosugi et al., 2004; Shimada
et al., 2005). Considering cut-off level of 2.5 ng mL-1
in this analysis, the positive rate will reach to 23.9% which is not significantly
different from the previous state. Shimada et al.
(2005) found that 34% of 103 patients with esophageal carcinoma had positive
marker which is nearly similar to present results. In their investigation all
cases had esophageal squamous cell carcinoma, but in several other studies SCCAg
was assessed in esophageal adenocarcinoma e.g., Mroczko
et al. (2008) reported the positive rate of 64% while 29% of their
cases had esophageal adenocarcinoma and the rest had esophageal squamous cell
||Relationship between SCCAg levels and clinicopathologic factors
in esophageal squamous cell carcinoma
In addition Sanchez De Cos et al. (1994) showed
elevated SCCAg levels in 47.7% of lung squamous cell carcinoma and 14.3% of
lung adenocarcinoma patients. Nevertheless the related measure is lower than
other studies given omission of esophageal adenocarcinoma cases.
The marker positivity of present cases has no relation with the tumor grade
and although it was lower in grade III carcinomas compared to low grade tumors,
the difference was not statistically significant. It has been suggested by some
investigations that SCCAg expression in patients with well differentiated squamous
cell carcinoma of esophagus is higher than cases with poorly differentiated
ones. In immunohistochemical study of SCCAg in esophagus tissue, Matsuda
et al. (1990) found that well differentiated tumors stained with
more intensity than poorly differentiated cases.
In the present study, 60% of metastatic (stage IV) patients were marker positive
which was higher than other stages. However, the difference was not significant.
In the study of Kosugi et al. (2004) SCCAg positivity
considerably correlated with stage of disease. Although some investigations
revealed the significant relationship between marker positivity in patients
with esophageal squamous cell carcinoma with tumor size, tumor depth and lymph
node involvement (Shimada et al., 2003, 2005),
seropositivity of SCCAg and high SCCAg mRNA level were shown not to be related
to stage in other studies (Honma et al., 2006;
Mroczko et al., 2008).
The only clinicopathologic feature of the patients with significant correlation with SCCAg positivity was tumor size. This finding also emerged in the study of cervix cancer patients in this center.
The prognostic value of serum SCCAg level has been confirmed by some survival
studies with a proper post treatment follow up. Takeuchi
et al. (2003) have shown the prognostic role of SCCAg level in the
serum of patients with lung adenocarcinoma but not in lung squamous cell carcinoma
cases. In both group they interestingly found that patients with preoperative
positive SCCAg who became negative after surgery had better prognosis compared
to patients who remained positive postoperatively.
Although, SCCAg marker was positive in minority of the patients, but considering its relation with tumor size and probability disease stage, it is suggested to carry out survival study on more cases to find out the relation between marker positivity and cancer recurrence.
This study was supported by funding from the Mashhad University of Medical Sciences. We also want to be thankful to the oncology staff of Ghaem and Omid Hospitals of Mashhad University of Medical Sciences for their respective contribution.