The median follow-up time of a total of 112 patients was 29.6 months. 76 (67.9%) were younger than 65 years old, 98 (87.5%) were male, 82 (73.2%) and 79 (70.5%) patients had a history of smoking and drinking alcohol, respectively. 99 (88.4%) patients had tumors located in the middle or lower third of the esophagus, and the clinical staging before surgery was predominantly cT3 in 87 patients (77.7%) and cN0 in one (0.9%). Postoperative pathology showed moderate and poor differentiation in 101 (90.2%) patients; further, surgical margin, nerve invasion, lymphvascular invasion (LVI) were positive in 3 (2.7%), 25 (22.3%), and 20 (17.9%) patients respectively. 52 (46.4%) patients have experienced recurrence. The post-neoadjuvant pathological stage was ypT0 in 27 patients (24.1%), ypT1–4 in 85 (75.9%), ypN0 in 20 (17.9%), and ypN1–3 in 92 (82.1%).
The correlation between clinicopathological characteristics and LNs responder status of 112 patients is shown in Table 1. Compared to nonresponders, responders showed significantly lower LVI (P = 0.021), lower proportions of ypT stage (P = 0.015), and ypN stage (P < 0.001) in terms of total LN-TRG. However, there were no significantly differences in age, sex, smoking, drinking, tumor location, differentiation, cT stage, cN stage, surgical margin, and nerve invasion between nonresponders and responders (P > 0.05) (Table 1).
In the univariate Cox regression analysis displayed in Table 2, age, sex, smoking, drinking, tumor location, differentiation, cT stage, cN stage, ypT stage, ypN stage, pCR(ypT0N0M0), pT-TRG, the AJCC pathological staging, and surgical margin were not significant prognostic factors affecting RFS, whereas nerve invasion, LVI, and LNs responder status (P < 0.05) were important predictors of RFS. In the multivariate Cox regression analysis, adjusted for these covariables that exhibited statistical significance in univariate analysis, LNs responder status (P < 0.05) was found to be an independent predictive factor for RFS. LNs non-responder status indicated higher recurrence risk [hazard ratio (HR) = 2.77; 95% confidence interval (CI):1.14–6.71; P = 0.024] (Table 2).
Figure 1 shows that HE was similar in morphology and controversial in interpretation. P40 (nucleus +) and PCK (cytoplasm +) on the left side were used to determine viable tumor cells (Fig. 1, Left side of BC), whereas P40 (nucleus -) and PCK (cytoplasm +) on the right side identified non-viable tumor cells (Fig. 1, Right side of BC).
The 3-year RFS rates for patients with LN-TRG of 1 to 4 grades were 72.7%, 76.5%, 37.4%, and 28.5%, respectively, and the median RFS times were 43.56 months, 28.09 months, 22.77 months, respectively. Notably, LN-TRG 1 was associated with a significant advantage of RFS compared with LN-TRG 3 (HR = 3.85; 95%CI: 1.43–10.41; P = 0.008) and 4 (HR = 3.09; 95%CI 1.23–7.73; P = 0.016). Furthermore, LN-TRG was discordant with PT-TRG in 83 (74.1%) patients, of which 60 (72.3%) had a higher LN-TRG than PT-TRG (Fig. 3A). Conversely, no significant differences were observed between PT-TRG 1–4, ypN0-3, or the AJCC pathological staging in stages 0-IVa (P > 0.05) (Fig. 3B-D).
Subgroup analysis, which divided into the patients into groups according to age, sex, smoking status, drinking status, PT responder status, is displayed in a forest plot. No significant difference was observed in the influence of LNs responder status on RFS in the subgroups (P for interaction > 0.05). LNs nonresponder status was an unfavorable prognostic factor for RFS in all subgroups, and the negative influence was more obvious in patients who were male, smokers, and drinkers (P < 0.05). Nevertheless, we observed that the influence of LNs responder status on RFS was significantly different in different subgroups, depending on whether there was PT response (P for interaction = 0.015). In the PT nonresponder group, LNs nonresponder status was also a significant negative predictive factor for RFS (HR = 5.56; 95% CI: 1.60-19.25; P = 0.007). (Fig. 2).
Figure 4 depicts LNs responder status in patients, the black dotted line indicates the tumor bed area, the red solid line indicates the viable tumor area, and the blue circle in the upper right corner is enlarged by the blue arrow (10X). Case 1: LN-TRG 4, the residual tumor rate was 80.0%, showing extensive residual tumor cells, swelling of cytoplasm, eosinophilia and disappearance of cell boundaries in a few tumors, with no obvious degeneration, interstitial fiber proliferation around the tumor, and disappearance of lymphatic follicles (Fig. 4A). Case 2: LN-TRG 3, the residual rate was 25.0%, showing that partial tumors remained, the tumor cells became eosinophilic, the nuclei were enlarged, lobulated and strangely shaped with apoptosis, and the tumor degeneration was obvious. At the same time, there were more fibrous hyperplasia and lymphoid follicles in the surrounding stroma of the tumor (Fig. 4B). Case 3: LN-TRG 2, the residual rate was 5.0%, showing minimal tumor residue, with eosinophilic and keratotic tumor cells and marked tumor degeneration. There was extensive fibrous proliferation in the peritumoral stroma with calcification, histiocytic response, and keratinization residue (Fig. 4C). Case 4: LN-TRG 1, the residual rate was 0.0%, and no tumor residue was observed except for fibrous hyperplasia, a histiocytic reaction, and keratinization (Fig. 4D).