A Simple Morphometric Analysis of Preoperative Therapy Response for Esophageal Adenocarcinoma

Histologic assessment of tumor regression grade (TRG) on esophagogastrectomy specimens after neoadjuvant therapy is an excellent predictor of local recurrence rate and long-term survival in esophageal adenocarcinomas. Although several grading systems exist globally, the modified Ryan system suggested by the College of American Pathologists (CAP) is widely used in North America. Most systems rely on quantitative percentage estimation of the residual tumor with or without additional qualitative descriptors, which is relatively subjective with poor interobserver agreement.

To test a morphometric-based approach using the microscopic objective lens to estimate the size of the largest focus of the residual tumor.

A total of 69 esophageal specimens post neoadjuvant therapy were evaluated. Tumor size was morphometrically determined by the microscopic field, using an Olympus microscope with ×10/×22 eyepieces. Residual viable tumor was categorized into 4 groups, using ×2, ×4, and ×10 objectives: ≤ ×10, > ×10 and ≤ ×4, > ×4 and < ×2, and ≥ ×2.

Morphometric measurements significantly correlated with the CAP treatment effect scores. There was no significant difference in overall survival between ≥ ×2 and ×2 to ×4 groups; however, a 3-tier system (TRG1: ≤ ×10, TRG2: > ×10 and ≤ ×4, and TRG3: > ×4) showed significant survival differences (P = .01). Significant differences in the percentage of lymphovascular and perineural invasion, advanced TNM stage, and lymph node metastasis were identified among the 3 groups.

The proposed 3-tier morphometric approach based on microscopic field size is a simple and easy-to-use method, which helps stratify patients into 3 groups with distinct histopathologic features and overall survival.