Background: In patients with gastric or gastroesophageal junction (GEJ) cancer treated with curative intent, distant interval metastases may be detected after start of neoadjuvant chemotherapy or during surgery. The aim of this study was to explore characteristics, allocated treatment and overall survival (OS) in gastric/GEJ cancer patients with interval metastases, and to compare OS with synchronous metastatic gastric/GEJ cancer patients who started palliative chemotherapy.
Methods: Patients with interval metastases were selected from the Netherlands Cancer Registry by including patients with potentially curable gastric/GEJ adenocarcinoma (2010-2018) who started chemotherapy without concurrent radiotherapy. The OS since start of neoadjuvant treatment of patients with interval metastases was compared with a propensity score-matched cohort of patients with synchronous metastases who received palliative systemic treatment.
Results: 164 patients with interval metastases diagnosed in 2010-2018 were included. Metastases were most frequently detected during surgery (83%) and most frequently located in the peritoneum (77%). Peritoneal interval metastases were observed in 63% and 80% of the patients who did and did not have a diagnostic laparoscopy prior to neoadjuvant treatment, respectively (P = 0.041). Median OS was 8.9 months (IQR 5.5-13.4), compared to 8.0 months (IQR 4.1-14.1) in matched synchronous metastatic patients calculated from start of neoadjuvant and palliative systemic treatment, respectively (P = 0.848).
Conclusion: This population-based study shows that gastric/GEJ cancer patients who started neoadjuvant treatment and were diagnosed with interval metastases most frequently suffered from peritoneal metastases detected during (exploratory) surgery, even when a diagnostic laparoscopy was performed before start of treatment. OS was comparable to patients with synchronous metastatic gastric/GEJ cancer.
Keywords: Drug therapy; Gastric neoplasms; Neoadjuvant therapy; Neoplasm metastases.
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