ESTRO 2025 - Abstract Book

S1754

Clinical – Upper GI

ESTRO 2025

Purpose/Objective: Gastric signet ring cellular carcinoma (GSRCC) is a highly invasive malignance and easy to recurrence and metastasis after surgical resection [1,2] . The prognosis for this disease is always poor in clinic. The results from the ARTIST and ARTIST-2 study both did not support the application of adjuvant radiotherapy after surgical resection for gastric adenocarcinoma [3.4] . However, the clinical significance of adjuvant radiotherapy is not clearly studied yet in the patients of GSRCC. This study focused the N+ GSRCC to explore the efficacy of radiotherapy in adjuvant setting. Material/Methods: We respectively collected the GSRCC patients in SEER database from the year of 2008 to 2018. The inclusion criteria comprised (1) GSRCC, diagnosed with pathology, staged from 1-3 and received radical surgery and perioperative chemotherapy; (2) had enough follow-up, treatment, staging and survival data; (3) the number of metastatic lymph node > 0. The exclusion criteria included (1) no pathologic diagnosis; (2) the information on follow-up, treatment and staging were not available; (3) the radiotherapy technique was intraoperative radiation therapy, isotope placement therapy rather than external beam radiation; (4) the metastatic disease or carcinoma in situ. Based on whether or not received post operation radiotherapy, we divided these patients into two groups: Radiotherapy Group and Control Group. If there was a baseline bias between the two groups, PSM would be used to balance. SPSS software, Kaplan Meier and Log-Rank test was used to analyze the statistics data. P value and HR was used to assess the significance in our study. Finally, the survival plot was made to show the cancer specific survival (CSS).

Results:

We include 197 N+ GSRCC cases who undergone with surgery and chemotherapy. In Radiotherapy group, there were 130 cases and 79 CSS events with 20 follow-up months. In Control group, there were 67 cases and 35 CSS events with 22 follow-up months. The baseline data between the two groups was well balanced. The median CSS in radiotherapy group and control group were 29.0 months and 19.0 months, respectively, with HR 0.58 (95% CI 0.39-0.88) and P =0.0044. Conclusion: Radiotherapy prolonged the survival on the basis of surgery and chemotherapy for patients with N+ GSRCC. Our study had vital clinical significance and worth to further study. Our study may help guide better treatment decisions and prolong the survival for this disease.

Keywords: Gastric Signet-Ring Cell Carcinoma, Radiotherapy

References: 1. Arai T. Where does signet-ring cell carcinoma come from and where does it go? Gastric Cancer. 2019 Jul;22(4):651 652.