The important role of circulating CYFRA21-1 in metastasis diagnosis and prognostic value compared with carcinoembryonic antigen and neuron-specific enolase in lung cancer patients

Although several tumor markers for lung cancer have been identified, none of them is specific for lung cancer diagnosis. CYFRA21-1 has been reported as a poor prognostic factor in various cancers, while NSE has been associated with metastasis, and also used for monitoring response to treatment in multiple myeloma. However, these important biomarkers have not been thoroughly investigated in lung cancer patients. In our study, analyses were performed to confirm the correlations between serums CEA, CYFRA 21–1, NSE, as well as the number of positive biomarkers and metastasis and survival status of lung cancer patients.

All patients were randomly divided into training and validation groups to confirm the grouping rationality of this study. In brief, survival curves and associations with clinical characteristics in the validation group were generally similar to those in training group, though there were some non-significant inconsistence in sex and several organs of metastasis. The results indicated that the increased levels of CYFRA21-1 were strongly associated with metastatic sites and histological grades of lung cancers in both training and validation groups. In specific histological subtypes (ADC, SCC and SCLC) analyses, we also found that CYFRA21-1 correlated more closely to metastasis and survival status than CEA and NSE. To our knowledge, these results have not been reported in any of the earlier literatures.

In multivariate Cox regression analysis, only CYFRA21-1 and NSE were found to be independent predictors of prognosis in lung cancer patients. When sub-grouped, only CYFRA21-1was an independent predictor of poor prognosis in ADC (1.86-fold increased risk in high concentration group) and SCLC (1.365-fold increased risk in moderate group) but not CEA and NSE. Finally it was found that CYFRA21-1 could act as independent factor in early (I + II) and advanced stages (III and IV) of lung cancer. Thus, CYFRA21-1 appears to be more important as a prognostic predictor than the other two biomarkers.

Several reports have reported the useful roles of CEA in diagnosis of ADC, CYFRA21-1 in SCC and NSE in SCLC [18–21]. The increased levels of biomarkers are known to correlate with cancer progression, with their sensitivity depending largely on tumor stage and histological classification [22]. In contrast with the previous reports [25], we found no correlation between increased CEA levels and brain metastasis; however, we did observe a correlation with bone, liver, pleural and peritoneal metastases. The inconsistency could be explained by the smaller sample size (approximate N = 300). Research also indicated that high circulating concentrations of CYFRA21-1 and CEA were associated with advanced stages of lung cancer; levels that were two times higher than cutoff value were associated with stage III and IV lung cancer patients [23]. Although CYFRA21-1 appears to be the most sensitive and specific marker for NSCLC [26], its relationship with different histological lung cancers has largely remained unknown. An earlier report suggested that CYFRA was a more sensitive and specific marker for SCC diagnosis and was found to be of prognostic values in patients with recurrent NSCLC receiving gefitinib therapy [27, 28]. In our study, however, high levels of CYFRA21-1 correlated with survival status in ADC and SCLC but not in SCC patients. It also could be used as an independent predictor of poor prognosis in ADC and SCLC patients. Currently, NSE is the most widely used marker for diagnosis and prognosis of SCLC patients [24]. In our study, although positive levels of NSE significantly correlated with survival in SCLC, it did not qualify as an independent predictor for poor prognosis.