Background: Esophageal cancer (EC) frequently presents with advanced stages, and is associated with high recurrence rates after esophagectomy. The value of an extended lymph node dissection (ELND) remains unclear in this setting.
Methods: An esophageal cancer data set was created through structured queries to the SEER 1973-2003 database. Relationships between the number of LNs examined and overall survival (OS) were analyzed for all histologic types.
Results: From a cohort of 40,129 patients, 7,971 individuals were selected based on completeness of information. The median age was 65 (range: 11-102), and 75% of patients were male. The median tumor size was 5.0 cm (0.1-30). On multivariate analysis, total LN count (or negative LN count, respectively) was an independent prognostic variable, aside from positive LN number, T category, tumor size, grade, age, year of diagnosis, radiation therapy (all at p<0.0001), gender (p=0.0008), histology (p=0.004), resection, M category, race (all at p=0.01), and primary site (p=0.02). Higher total LN count (up to >30) and negative LN count (up to >15) categories were associated with the best OS (p<0.0001, see Table and Figures).
Conclusions: More extensive LN dissection and analysis influence EC survival. Survival prediction depends on both total LN number and number of negative LNs obtained. While the mechanism remains uncertain, ELND during potentially curative esophagectomy for EC can be supported by the data.
Overall Survival, by total and negative LN counts

Category	Subgroup	n	Median OS	1-year OS	2-year OS	5-year OS	10-year OS
Total LN counts	0 LNs examined	8113	8 months	36%	20%	9%	5%
	1 LN	370	1.1 years	51%	32%	18%	10%
	2-4 LNs	777	1.6 years	62%	44%	25%	13%
	5+ LNs	2853	1.8 years	67%	47%	28%	18%
Negative LN counts	0 LNs negative	312	8 months	34%	13%	5%	4%
	1-2 LN negative	701	1.2 years	54%	35%	20%	14%
	3+ LNs negative	2972	2.1 years	70%	51%	31%	18%