Segment-specific patterns of regional lymph-node metastasis in primary small-cell carcinoma of the esophagus: A systematic review and meta-analysis

Table 1 Surgical cohorts included in the patient-level pathologic lymph-node metastasis prevalence meta-analysis

Ref.	Setting	Patients	Node-positive patients	Crude prevalence	Role in synthesis
Wu et al[11]	Limited-stage Chinese surgical series	21	15	71.4%	Small surgical denominator; directionally useful
Xu et al[8]	Retrospective resected SCCE cohort	125	60	48.0%	Patient-level and dissected-node denominator
Liu et al[9]	Detailed thoracic SCCE station-level cohort	147	100	68.0%	Main peer-reviewed station-level anchor
CHiSCEC[13]	Multicenter preprint with surgical denominator	286	177	61.9%	Largest denominator; interpreted cautiously
Random-effects synthesis	Logit-transformed proportions	579	352	61.1% pooled	95%CI: 51.4% to 70.0%; I² = 76.4%

SCCE: Small cell carcinoma of the esophagus.

Table 2 Segment-specific station-level interpretation for multidisciplinary planning

Tumor segment	Dominant signal	Supporting evidence	Practical interpretation
Upper thoracic SCCE	Upper mediastinal and recurrent laryngeal nerve involvement; CHiSCEC high-risk stations No. 105, No. 106recR, and No. 106recL	Liu et al[9]; CHiSCEC[13]; Jiao et al[10]	upper mediastinal nodal assessment should be explicit; lower mediastinal assessment remains warranted when imaging, tumor length, or pathology suggests risk
Middle thoracic SCCE	Most diffuse pattern, including upper and middle mediastinal, recurrent nerve, perigastric, and abdominal compartments; CHiSCEC high-risk stations No.107, No. 108, and abdominal No. 7	Liu et al[9]; CHiSCEC[13]; Wu et al[11]	Bidirectional nodal evaluation is more defensible than a narrow peritumoral field
Lower thoracic SCCE	Dominant lower mediastinal, perigastric, and abdominal signal; CHiSCEC high-risk stations No. 107, No. 110, abdominal No. 2, and abdominal No. 7	Liu et al[9]; CHiSCEC[13]	Upper abdominal and perigastric risk should be weighed against operative and radiotherapy morbidity; upper mediastinal skip risk remains possible
Cross-segment issue	Skip metastasis and named station risk are clinically relevant but not yet independently linked to survival	Liu et al[9]; Xu et al[8]; CHiSCEC[13]	Standardized station reporting is needed before classical efficacy-index or station-specific survival claims can be made

SCCE: Small cell carcinoma of the esophagus.

Table 3 Main limitations and safeguards applied in the review

Issue	Risk to inference	Safeguard used here
Retrospective surgical cohorts	Selection bias and variable treatment sequence	Pooled only compatible pathologic surgical denominators; interpreted estimates as surgical-series probabilities
Heterogeneous station maps	Invalid formal station-by-segment pooling	Summarized station evidence as an evidence map
Preprint evidence	Non-peer-reviewed data and possible cohort-overlap uncertainty	Included CHiSCEC for completeness, flagged its preprint status and possible overlap with Xu et al[8], and performed an overlap sensitivity analysis[8,13]
Node-level clustering	Individual nodes are not independent observations	Reported node-level metastatic ratios descriptively only
Unavailable station-positive survival endpoints	Station-specific survival benefit and efficacy index cannot be estimated	Avoided claims that treating any specific station improves survival