Comments on “Treatment Strategies and Prognostic Factors of Limited-Stage Primary Small Cell Carcinoma of the Esophagus”

Abstract

occurred in separate cellular clones. The level of the C797S mutation is expected to be similar to or lower than the level of the T790M mutation if both mutations are present in the same cells, and it would show either concomitant increase or decrease in response to the combination therapy. The levels of each EGFR mutation measured by digital droplet polymerase chain reaction from a series of plasma samples indicated that the T790M and C797S mutations were likely present in different tumor cells, a finding that as we suggested in our article, may be due to multiple clones with individual mutations and resultant differences in tyrosine kinase sensitivity. 3 In the blood collected before the combination therapy, the levels of the T790M and C797S mutations were detected at mutant allele frequencies of 2.8% and 4.5%, respectively. This indicates that the overall load of C797S-positive tumor was higher than that of T790M-positive tumor before the combination therapy. The observed clinical improvement without reduction in T790M or exon 19 deletion also supports this hypothesis of clonal heterogeneity rather than the mutation being present in the same cells. Definitive proof, however, would require single-cell analysis, which is not possible for this patient.

Response to “Comments on Treatment Strategies and Prognostic Factors of Limited-Stage Primary Small Cell Carcinoma of the Esophagus”

“…In summary, we would like to express our deep thanks to Safiri et al 1 for their interest in our article and their valuable comments. In our article, we tried to report the characteristics of the patients with PSCCE in details, adjust the independent prognostic factors, and analyze the best options for treatment of PSCCE in different stages.…”

“…We would like to thank Safiri et al for their interest in our article and for their helpful comments. 1 We have carefully reviewed both the comments and our article and the following is our response.…”

“…First, we retrospectively analyzed the data on 152 consecutive patients with limited-stage primary small cell carcinoma of the esophagus (PSCCE) who received treatment at the Affiliated Cancer Hospital of Zhengzhou University. 2 Safiri et al 1 mentioned that the included patients were treated in a tertiary care center and that selection bias may exist. This bias may be because the patients included in our study may differ from those who did not participate in our study in terms of having different characteristics, such as socioeconomic status.…”

“…Safiri et al 1 stated that the authors should have better reported the background characteristics of the patients in detail and adjusted the effect of these characteristics on survival. Today, we are not sure whether these characteristics have an effect on survival.…”

“…Safiri et al 1 were uncertain whether we performed univariate analysis for selecting the significant predictors for multivariable model and how the multivariable analysis was done. We hereby clarify that univariate analysis was used for selecting the predictors.…”