Fig. 3

Kaplan–Meier curves for overall survival (a) and relapse-free survival (b) according to adjuvant chemotherapy durations in patients with gastric cancer. The duration of adjuvant chemotherapy was less than 6 months [group 1] in 147 patients (34.2 %), from 6 months to less than 12 months [group 2] in 94 patients (21.9 %), from 1 year to less than 2 years in [group 3] 139 patients (32.3 %), and over 2 years [group 4] in 50 patients (11.6 %). The reference category of Cox regression analysis in Fig. 3a, b is no adjuvant treatment or surgery-only group. Five-year OS rates for groups 1, 2, 3, and 4 were 75.7 % (HR 1.478, 95 % CI 0.833–2.62, p = 0.182), 87 % (HR 1.140, 95 % CI, 0.555–2.344, p = 0.721), 90.3 % (HR 0.522, 95 % CI 0.254–1.071, p = 0.076), and 93.4 % (HR 0.437, 95 % CI 0.151–1.264, p = 0.127), respectively. The 3-year RFS rates for groups 1, 2, 3, and 4 were 52.5 % (HR 2.099, 95 % CI 1.449–3.040, p = 0.000), 58.8 % (HR 1.584, 95 % CI 1.029–2.438, p = 0.037), 81.4 % (HR 0.737, 95 % CI 0.476–1.142, p = 0.172), and 94.0 % (HR 0.537, 95 % CI 0.272–1.061, p = 0.074), respectively [Fig. 3]. p values were calculated with the use of the stratified log-rank test