Initial Gastrectomy Indication Is Associated with Divergent Temporal Patterns of Remnant Gastric Cancer After Billroth II Reconstruction: A Retrospective Study

Background: Remnant gastric cancer (RGC) may develop over markedly different intervals after gastrectomy. We investigated the time-dependent clinicopathological patterns of RGC after Billroth II reconstruction and their implications for endoscopic surveillance. Methods: We retrospectively reviewed patients diagnosed with RGC at West China Hospital between October 2012 and October 2022. Patients were classified by the indication for initial gastrectomy (malignant or benign disease) and the interval to RGC detection (≤3 years, >3 to ≤10 years, and >10 years). Results: Sixty-one patients were included; 39 (63.9%) had tumors at the anastomotic site. Histology was classifiable in 48 patients, of whom 45 had undifferentiated carcinoma (93.8%; 73.8% of the total cohort). The interval to RGC detection was shorter in the carcinoma group than in the benign-disease group (4.8 ± 5.7 vs. 31.6 ± 12.9 years, p < 0.001). Eighteen of 36 patients (50.0%) in the carcinoma group were diagnosed within 3 years, whereas 23 of 25 patients (92.0%) in the benign-disease group were diagnosed after 10 years. All 18 RGCs diagnosed ≤3 years after the initial gastrectomy occurred in patients whose initial indication was gastric carcinoma. In exploratory unadjusted pairwise comparisons among patients with known distant-metastasis status, distant metastasis was more frequent in the ≤3-year group than in the >10-year group (11/17 [64.7%] vs. 6/25 [24.0%], p = 0.012), whereas surgery for RGC was less frequent (5.6% vs. 53.8%, p = 0.001). Conclusions: RGC after Billroth II reconstruction showed distinct temporal patterns. Associations with metastatic burden and surgical treatment were exploratory, and the effects of postoperative interval and initial indication could not be reliably separated. These hypothesis-generating findings require prospective validation before specific surveillance intervals can be recommended.