Table 1 shows patients’ clinicopathological factors. Among the 67 patients, 5 and 62 had clinical T3 and T4 tumors, respectively. With regard to lymph node metastasis, 23, 12, 17, and 15 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. Seven 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 and 34 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 patients underwent total gastrectomy and one underwent proximal gastrectomy. Moreover, D1, D1+, and D2 lymphadenectomy was performed in 2, 6, and 15 patients, respectively. As two patients had no viable tumor cells in the primary site, the depth of tumor invasion was staged as T0. However, 1, 5, and 15 patients had a pathological T2, T3, and T4 tumors, respectively. Furthermore, 9, 2, and 12 patients had a pathological N0, N1, and N3, respectively. R0, R1, and R2 resection was performed in 21, 1, and 1 patient, respectively. Eighteen, 1, 2, and 2 patients had the histological response of grade 1a, 1b, 2, and 3, respectively.
Correlation 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, first-line chemotherapeutic regimen, lymph node metastasis (cN0-1 vs. cN2-3), tumor response, and presence or absence of surgery were significantly associated with survival between surgery and non-surgery groups (p = 0.0394, p = 0.0311, p = 0.0006, p < 0.0001, and p < 0.0001, respectively) (Table 4). Multivariate analysis selected tumor response and surgery as an independent prognostic factor (p = 0.0001 and p = 0.0009, respectively) (Table 4).
Univariate and multivariate analyses in the surgery group alone
Univariate analysis showed that lymph node metastasis (pN0-1 vs. pN2-3) and residual tumor status (R0 vs. R1-2) were significantly correlated with survival in the surgery group (p = 0.0121 and p = 0.0096, respectively) (Table 5). Similarly, multivariate analysis indicated that lymph node metastasis and residual tumor status were identified as independent prognostic factors (p = 0.0258 and p = 0.0458, respectively) (Table 5).