Table 1 shows patients’ clinicopathological factors. Among the 67 patients, 5 (7.5%) and 62 (92.5%) had clinical T3 and T4 tumors, respectively. With regard to lymph node metastasis, 23 (34.3%), 12 (17.9%), 17 (25.4%), and 15 (22.4%) patients had clinical nodal status of N0, N1, N2, and N3, respectively. Distant metastasis was observed in 58 patients, with at least peritoneal dissemination in 55 patients (82.1%). Seven (10.4%) had more than two distant metastatic sites. Among them, 5, 5, 1, and 1 had liver metastasis, distant lymph node metastasis, ovarian metastasis, and metastasis of the small intestine, respectively.
Among 67 patients enrolled in this study, 33 (49.3%) and 34 (50.7%) underwent platinum- and taxane-based chemotherapy as a first-line regimen, respectively. Furthermore, 8 patients with positive human epidermal growth factor receptor 2 expression received trastuzumab combined with chemotherapy.
Tumor response and survival after chemotherapy
Concerning the tumor response to chemotherapy, 16 and 51 patients had PD and non-PD, respectively. Therefore, the disease control rate was 76.1% (51/67). The median survival durations of pAtients with PD and those with non-PD were 159 and 757 days, respectively (Fig.1). The survival difference based on tumor response was statistically significant (p < 0.0001).
Surgery after chemotherapy and pathological findings
A total of 23 patients (34.3%) underwent surgery after chemotherapy. Surgical procedures and pathological findings are shown in Table 2. Twenty-two (95.7%) patients underwent total gastrectomy and one (4.3%) underwent proximal gastrectomy. Moreover, D1, D1+, and D2 lymphadenectomy was performed in 2 (8.7%), 6 (26.1%), and 15 (65.2%) patients, respectively. As two (8.7%) patients had no viable tumor cells in the primary site, the depth of tumor invasion was staged as T0. However, 1 (4.3%), 5 (21.7%), and 15 (65.2%) patients had a pathological T2, T3, and T4 tumors, respectively. Furthermore, 9 (39.1%), 2 (8.7%), and 12 (52.2%) patients had a pathological N0, N1, and N3, respectively. R0, R1, and R2 resection was performed in 21 (91.3%), 1 (4.3%), and 1 (4.3%) patient, respectively. Eighteen (78.3%), 1 (4.3%), 2 (8.7%), and 2 (8.7%) patients had the histological response of grade 1a, 1b, 2, and 3, respectively.
Relationship between the presence or absence of surgery and clinicopathological factors
The mean age (± standard deviation [SD]) of the surgery (n = 23) and non-surgery (n = 44) groups was 58.0 ± 13.7 and 64.9 ± 12.6 years, respectively (Table 3). Consequently, the presence or absence of surgery was significantly correlated with age (p = 0.0412). Moreover, surgery was significantly associated with the first-line chemotherapeutic regimen, lymph node metastasis, clinical stage, number of distant metastatic sites, and peritoneal dissemination (p = 0.0096, p = 0.0024, p = 0.0059, p = 0.0128, and p = 0.0020, respectively) (Table 3). Among 23 patients in the surgery group, 22 (95.7%) had non-PD as tumor response, whereas 15 patients (34.1%) had PD among the 44 patients in the non-surgery group. Accordingly, tumor response was significantly associated with the presence or absence of surgery (p = 0.0066) (Table 3).
Survival assessment in both surgery and non-surgery groups
The 3-year OS rate of surgery and non-surgery groups was 56.4% and 6.2%, respectively (p < 0.0001) (Fig. 2).
Univariate analysis demonstrated that age (hazard ratio [HR] 1.832, p = 0.0394), first-line chemotherapeutic regimen (HR 0.529, p = 0.0311), lymph node metastasis (cN0-1 vs. cN2-3) (HR 2.728, p = 0.0006), tumor response (HR 6.604, p < 0.0001), and presence or absence of surgery (HR 0.178, p < 0.0001) were significantly associated with survival between surgery and non-surgery groups (Table 4). Multivariate analysis selected tumor response (HR 4.123, p = 0.0001) and surgery (HR 0.229, p = 0.0009) as an independent prognostic factor (Table 4).
Univariate and multivariate analyses in the surgery group alone
Univariate analysis showed that lymph node metastasis (pN0-1 vs. pN2-3) (HR 5.517, p = 0.0121) and residual tumor status (R0 vs. R1-2) (HR 13.672, p = 0.0096) were significantly correlated with survival in the surgery group (Table 5). Similarly, multivariate analysis indicated that lymph node metastasis (HR 4.786, p = 0.0258) and residual tumor status (HR 7.655, p = 0.0458) were identified as independent prognostic factors (Table 5).