Solitary intracranial metastasis as the sole relapse site in gastric cancer patients after neoadjuvant therapy and surgery: a case series of 12 patients and clinical implications.

Background: Gastric cancer recurrence commonly involves the peritoneum, liver, and lungs, whereas isolated intracranial metastasis is rare, particularly in patients receiving neoadjuvant therapy and surgery. This study aimed to characterize a distinct subgroup of patients with isolated intracranial recurrence after neoadjuvant treatment and radical surgery. Methods: We retrospectively reviewed patients with gastric cancer who underwent neoadjuvant therapy followed by curative resection and subsequently developed isolated intracranial metastasis confirmed by whole-body imaging. Clinical and pathological features were systematically analyzed. Results: Twelve patients met the inclusion criteria. All patients were lymph node-positive (100%). The primary tumor was located at the cardia or esophagogastric junction in 11 patients (91.7%). Poorly differentiated histology was observed in eight patients (66.7%), while the remaining four (33.3%) had moderately differentiated tumors; no well-differentiated cases were identified. The median time from surgery to intracranial metastasis was 15.3 months (95% confidence interval: 9.0-21.6 months). Conclusions: Isolated intracranial metastasis after neoadjuvant therapy for gastric cancer is associated with a distinct clinical profile: cardia/esophagogastric junction location, positive lymph node status, and poorly differentiated histology. Recognition of this high-risk profile may facilitate early diagnosis and inform surveillance strategies in this patient population.