International Retrospective Cohort Study of Conversion Therapy for Stage IV Gastric Cancer 1 (CONVO-GC-1)

Abstract

Aim: Much attention has been paid to conversion therapy for stage IV gastric cancer, however, its operative comorbidities and survival benefit have not yet been clarified. CONVO-GC-1, an international retrospective cohort study, was designed to investigate the role of conversion surgery in Japan, Korea, and China.

Methods: The rate of operative complications was the primary endpoint and the overall survival (OS), according to the four-category criteria previously published (Gastric Cancer:19; 2016), was analyzed as the secondary endpoint.

Results: A total of 1206 patients underwent surgery after chemotherapy with curative intent. Operative complications were observed in 290 (24.0%) patients in all grades, including pancreatic fistula and surgical site infection. The median survival time (MST) of all resected patients was 36.7 mo (M) and those of R0, R1, and R2 resection were 56.6 M, 25.8 M, and 21.7 M, respectively. Moreover, the MST of R0 patients were 47.8 M, 116.7 M, 44.8 M in categories 1, 2, and 3, respectively, and not reached in category 4. Interestingly, the MST of P1 patients was as favorable as that of P0CY1 patients if R0 resection was achieved. The MST of patients with liver metastasis was also favorable regardless of the number of lesions, and the MST of patients with para-aortic lymph node (LN) No 16a1/b2 metastasis was not inferior to that of patients with para-aortic LN No 16a2/b1 metastasis.

Conclusion: Conversion therapy for stage IV gastric cancer is safe and could be a new therapeutic strategy to improve the survival of patients, especially those with R0 resection.

Keywords: adjuvant surgery; chemotherapy; conversion therapy; gastric cancer; metastatic gastric cancer.

FIGURE 1

Flowchart of patient recruitment. 2≤ sites, patients with metastases in more than one organ are all classified into each category; 1 site, patients with metastasis in one organ classified into each category; P0, absence of peritoneal dissemination; P1, presence of peritoneal dissemination; CY0, negative peritoneal cytology; CY1, positive peritoneal cytology; CYX, cytology not performed; 16a2/b1, para‐aortic lymph node in station number 16a2/b1; LN, lymph node

FIGURE 2

Kaplan–Meier curves for overall survival (A) of all patients; the median survival time (MST) of all 1206 patients who underwent conversion therapy was 36.7 mo (95% confidential interval [CI]: 34.4–40.0), (B) of patients stratified with category classification; the MST was 38.4 mo (33.5–44.1) in category 1, 46.6 mo (35.3–82.2) in category 2, 33.4 mo (29.4–37.0) in category 3, and 34.1 mo (26.9–47.5) in category4, (C) of all patients stratified with the status of residual tumor in conversion surgery; the MST was 56.6 mo (46.4–74.5) in patients with R0 resection, 25.8 mo (22.4–30.2) in patients with R1 resection, and 21.7 mo (18.6–22.8) in patients with R2 resection (P < .001), (D) of patients in category 1 stratified with the status of residual tumor in conversion surgery; the MST was 47.8 mo (40.7–95.2) in patients with R0 resection, 24.4 mo (20.7–30.2) in R1 resection, and 20.9 mo (15.2–24.1) in R2 resection (P < .001), as well as (E) in category 2 [MST was 116.7 mo (61.2–not reached) in patients with R0 resection, 22.1 mo (18.5–32.5) in patients with R1 resection, and 22.8 mo (19.2–25.8) in patients with R2 resection (P < .001)], (F) in category 3 [MST was 44.8 mo (37.9–60.4) in patients with R0 resection, 30.4 mo (20.6–37.0) in patients with R1 resection, and 18.5 mo (17.4–22.6) in patients with R2 resection (P < .001)], and (G) in category 4 [MST was not reached (37.2–not reached) in patients with R0 resection, 23.4 mo (15.1–29.4) in patients with R1 resection, and 23.5 mo (17.7–32.3) in patients with R2 resection (P < .001)]

FIGURE 3

A flowchart of the new treatment strategy to apply conversion surgery for advanced gastric cancer patients