Impacts of neoadjuvant therapy on the number of dissected lymph nodes in esophagogastric junction cancer patients

BACKGROUND: Neoadjuvant therapy favors the prognosis of various cancers, including esophagogastric junction cancer (EGC). However, the impacts of neoadjuvant therapy on the number of dissected lymph nodes (LNs) have not yet been evaluated in EGC. METHODS: We selected EGC patients from the Surveillance, Epidemiology, and End Results (SEER) database (2006–2017). The optimal number of resected LNs was determined using X-tile software. Overall survival (OS) curves were plotted with the Kaplan–Meier method. Prognostic factors were evaluated using univariate and multivariate COX regression analyses. RESULTS: Neoadjuvant radiotherapy significantly decreased the mean number of LN examination compared to the mean number of patients without neoadjuvant therapy (12.2 vs. 17.5, P = 0.003). The mean LN number of patients with neoadjuvant chemoradiotherapy was 16.3, which was also statistically lower than 17.5 (P = 0.001). In contrast, neoadjuvant chemotherapy caused a significant increase in the number of dissected LNs (21.0, P < 0.001). For patients with neoadjuvant chemotherapy, the optimal cutoff value was 19. Patients with > 19 LNs had a better prognosis than those with 1–19 LNs (P < 0.05). For patients with neoadjuvant chemoradiotherapy, the optimal cutoff value was 9. Patients with > 9 LNs had a better prognosis than those with 1–9 LNs (P < 0.05). CONCLUSIONS: Neoadjuvant radiotherapy and chemoradiotherapy decreased the number of dissected LNs, while neoadjuvant chemotherapy increased it in EGC patients. Hence, at least 10 LNs should be dissected for neoadjuvant chemoradiotherapy and 20 for neoadjuvant chemotherapy, which could be applied in clinical practice.