Impact of duration of adjuvant chemotherapy in radically resected patients with T4bN1-3M0/TxN3bM0 gastric cancer

AIM: To provide evidence regarding the postoperative treatment of patients with T4bN1-3M0/TxN3bM0 gastric cancer, for which guidelines have not been established. METHODS: Patients who had undergone curative resection between 1996 and 2014 with a pathological stage of T4bN1-3M0/TxN3bM0 for gastric cancer were retrospectively analyzed; staging was based on the 7th edition of the American Joint Committee on Cancer staging system. The clinicopathological characteristics, administration of adjuvant chemotherapy, and patterns of recurrence were studied. Univariate and multivariate analyses of prognostic factors were conducted. The chemotherapeutic agents mainly included fluorouropyrimidine, platinum and taxanes, used as monotherapy, doublet, or triplet regimens. Patterns of first recurrence were categorized as locoregional recurrence, peritoneal dissemination, or distant metastasis. RESULTS: The 5-year overall survival (OS) of the whole group (n = 176) was 16.8%, and the median OS was 25.7 mo (95%CI: 20.9-30.5). Lymphovascular invasion and a node positive rate (NPR) ≥ 0.8 were associated with a poor prognosis (P = 0.01 and P = 0.048, respectively). One hundred forty-seven (83.5%) of the 176 patients eventually experienced recurrence; the most common pattern of the first recurrence was distant metastasis. The prognosis was best for patients with locoregional recurrence and worst for those with peritoneal dissemination. Twelve (6.8%) of the 176 patients did not receive adjuvant chemotherapy, while 164 (93.2%) patients received adjuvant chemotherapy. Combined chemotherapy, including doublet and triplet regimens, was associated with a better prognosis than monotherapy, with no significant difference in 5-year OS (17.5% vs 0%, P = 0.613). The triplet regimen showed no significant survival benefit compared with the doublet regimen for 5-year OS (18.5% vs 17.4%, P = 0.661). Thirty-nine (22.1%) patients received adjuvant chemotherapy for longer than six months; the median OS in patients who received adjuvant chemotherapy for longer than six months was 40.2 mo (95%CI: 30.6-48.2), significantly longer than the 21.6 mo (95%CI: 19.1-24.0) in patients who received adjuvant chemotherapy for less than six months (P = 0.001). CONCLUSION: Patients with T4bN1-3M0/TxN3bM0 gastric cancer showed a poor prognosis and a high risk of distant metastasis. Adjuvant chemotherapy for longer than six months improved outcomes for them.