Unexpected Microscopically Positive Proximal Resection Margins in Esophageal Squamous Cell Carcinoma After Chemoradiotherapy: Predictors and Prognostic Significance

Background: Esophageal cancer has the propensity to spread in a longitudinal manner (either proximally or distally), potentially resulting in the unexpected presence of microscopic disease at grossly tumor-free margins. The clinical significance of this phenomenon in patients treated with chemoradiotherapy (CRT) remains unclear. The purpose of this study was to investigate the prevalence, predictors, and prognostic impact of microscopically positive proximal resection margins (PPRMs) in patients with esophageal squamous cell carcinoma (ESCC) who received CRT. Methods: Between 2000 and 2014, we identified 332 ESCC patients who underwent complete gross resection (R0/R1) following CRT. Patients were divided into two groups according to the status of the proximal resection margins on microscopic examination [negative proximal resection margins (NPRMs) vs PPRMs]. The occurrence of anastomotic leakage (AL) and anastomotic recurrence (AR) served as outcome measures. Results: Sixteen (4.8 %) patients had PPRM. The presence of PPRM was not associated with AL but was a strong predictor of AR (PPRM vs NPRM, 23.1 vs 7 %, respectively, P = 0.033). Multivariate analysis identified a resection margin length <3.5 cm [odds ratio (OR) 4.473, P = 0.022] and salvage resection (OR 3.171, P = 0.045) as independent predictors of PPRM. The estimated PPRM rates were 16.7, 6.3, and 1.3 % for patients with 2, 1, and 0 predictors, respectively. Conclusions: PPRM occurred in 4.8 % of ESCC patients following CRT and was associated with AR. An intraoperative frozen section margin analysis should be performed in patients carrying risk factors to avoid unexpected PPRM.