The role of endoscopic ultrasound in assessing tumor response and staging after neoadjuvant chemotherapy for esophageal cancer

Although the role of endoscopic ultrasound (EUS) in the initial staging of esophageal cancer is well established, its role in assessing tumor response and staging esophageal cancers after neoadjuvant chemotherapy (NAC) is controversial, and this study aimed to investigate this role.

This study retrospectively analyzed 110 patients with esophageal cancer who underwent EUS by single surgeon before and after NAC. Tumor response was assessed before and after NAC. Patients with more than a 50% reduction in tumor size based on EUS evaluation were classified as having a significant response to chemotherapy, and those with less than a 50% reduction were categorized as having a partial response. Disease stage was established by tumor node metastasis (TNM) classification. Initial staging was performed using EUS and computed tomography (CT) scans of the chest and abdomen. The EUS-determined stage was compared with the postsurgical pathologic stage. χ² analysis and Fisher’s exact testing were performed.

A response to NAC was shown by 96 patients (87.3%) and no response by 14 patients (12.7%). Of the 96 responding patients, 37 (38.5%) showed a significant response, whereas 43 (61.5%) of 69 patients showed a partial response. The EUS staging correlated well with the pathologic staging for 9 (64.3%) of the 14 nonresponders and for 34 (35.4%) of the 96 responders to NAC (P = 0.04). The EUS accurately predicted both the T and N status for 26 (23.6%) of the 110 patients. Prediction of N status was significantly more accurate than prediction of the T stage for the post-NAC patients. Of the 110 patients, 43 (39.1%) patients had an accurate T-stage prediction, and 64 (58.2%) had an accurate N stage match (P = 0.02). The T stage was overstaged for 60 (54.5%) of the patients and understaged for 7 of the patients (6.4%).The study found overstaging of the T stage to be more common among the patients who responded to chemotherapy. The N stage was overstaged for 25 (22.7%) and understaged for 21 (19.1%) of the 110 patients.

The findings showed EUS to be a useful tool for assessing response to chemotherapy and for evaluating the extent of disease, thus facilitating surgical decision making. However, EUS is an unreliable tool for staging esophageal cancer after NAC. Overstaging of the T stage is significantly more common and could be related to the inflammatory effect or fibrosis after NAC.