Prognostic effect of excessive chemotherapy cycles for stage II and III gastric cancer patients after D2 + gastrectomy

Table 1 Patient characteristics before and after propensity score matching based on the number of chemotherapy cycles for stage II gastric cancer

Variables	Before PSM		P value	After PSM		P value
	< 9 cycles, n = 125	≥ 9 cycles, n = 287		< 9 cycles, n = 97	≥ 9 cycles, n = 97
Sex			0.022			0.718
Male	95	245		77	79
Female	30	42		20	18
Age in yr	55.38 ± 10.91	60.44 ± 9.85	< 0.001	56.46 ± 10.10	56.46 ± 10.10	0.215
Depth of tumor invasion			0.248			0.998
T1	7	6		5	4
T2	11	18		10	10
T3	79	195		60	62
T4	28	68		22	21
Number of positive lymph nodes			0.064			0.740
0	64	172		52	49
1-2	53	107		39	43
3-6	4	5		4	3
≥ 7	4	3		2	2
Type of gastrectomy			0.448			0.249
Proximal	14	24		10	8
Distal	41	93		32	26
Total	0	170		55	63
Vascular invasion			0.561			0.468
Negative	77	168		54	59
Positive	48	119		42	38
Neural invasion			0.719			1.000
Negative	79	176		64	64
Positive	46	111		33	33
Lauren classification			0.793			0.493
Intestinal	60	143		47	52
Diffuse	27	58		21	19
Mixed	38	86		29	26
Maximum diameter of tumor in cm			0.603			0.410
< 6	87	207		70	75
≥ 6	38	80		27	22
Surgical margin			0.740			0.562
Negative	123	281		95	96
Positive	2	6		2	2
HER2			0.337			0.911
Negative	70	171		55	54
Positive	55	116		42	43

PSM: Propensity score matching.

Table 2 Subgroup analysis of overall survival by Cox regression analysis of stage II gastric cancer patients

Variables	Death	Total	HR	95%CI	P value	P for interaction
Sex						0.219
Male	33	156	0.966	0.486-1.919	0.922
Female	6	38	0.520	0.095-2.852	0.452
Depth of tumor invasion						0.749
T1/T2	7	29	0.745	0.164-3.382	0.702
T3/T4	32	165	0.908	0.451-1.828	0.786
Number of positive lymph nodes						0.458
0	21	101	0.584	0.236-1.450	0.247
≥ 1	18	93	1.254	0.492-3.194	0.635
Vascular invasion						0.729
Negative	24	128	1.474	0.535-4.061	0.431
Positive	15	66	0.679	0.246-1.870	0.453
Neural invasion						0.937
Negative	36	163	1.035	0.465-2.306	0.932
Positive	22	93	0.709	0.241-2.083	0.531
Lauren classification						0.553
Intestinal	16	99	0.931	0.568-1.526	0.766
Diffuse	11	40	0.755	0.228-2.506	0.647
Mixed	12	55	1.014	0.570-1.802	0.963
Maximum diameter of tumor in cm						0.167
< 6	20	145	0.986	0.410-2.375	0.976
≥ 6	19	49	0.807	0.317-2.054	0.653
Type of gastrectomy						0.664
Proximal	4	18	1.029	0.378-2.804
Distal	9	58	1.103	0.296-4.111
Total	26	118	0.850	0.575-1.256
HER2						0.656
Negative	21	109	0.858	0.361-2.040
Positive	18	85	0.869	0.343-2.204

CI: Confidence interval; HR: Hazard ratio.

Table 3 Subgroup analysis of progression-free survival by Cox regression analysis of chemotherapy cycles of stage II gastric cancer

Variables	Death or recurrence	Total	HR	95%CI	P value	P for interaction
Sex						0.385
Male	33	156	0.788	0.426-1.459	0.449
Female	22	38	0.495	0.149-1.646	0.252
Depth of tumor invasion						0.226
T1/T2	9	29	0.827	0.227-3.109	0.779
T3/T4	46	165	0.670	0.368-1.219	0.190
Number of positive lymph nodes						0.842
0	28	101	0.519	0.232-1.159	0.110
≥ 1	27	93	0.895	0.420-1.905	0.773
Vascular invasion						0.743
Negative	23	128	1.225	0.536-1.798	0.630
Positive	32	66	0.454	0.200-0.988	0.047
Neural invasion						0.732
Negative	35	163	0.649	0.328-1.286	0.216
Positive	20	93	0.878	0.348-2.212	0.782
Lauren classification						0.622
Intestinal	20	99	0.833	0.344-2.015	0.685
Diffuse	15	40	0.582	0.207-1.639	0.306
Mixed	20	55	0.839	0.323-2.177	0.718
Maximum diameter of tumor in (cm)						0.128
< 6	33	145	0.642	0.317-1.301	0.219
≥ 6	22	49	0.883	0.370-2.106	0.779
Type of gastrectomy						0.356
Proximal	5	18	0.716	0.115-4.443	0.720
Distal	17	58	0.521	0.181-1.501	0.227
Total	35	118	0.779	0.389-1.503	0.483
HER2						0.200
Negative	29	109	0.851	0.408-1.772	0.665
Positive	26	85	0.549	0.242-1.245	0.151

CI: Confidence interval; HR: Hazard ratio.

Table 4 Patient characteristics before and after propensity score matching based on the number of chemotherapy cycles for stage III gastric cancer

Variables	Before PSM		P value	After PSM		P value
	< 9 cycles, n = 278	≥ 9 cycles, n = 624		< 9 cycles, n = 242	≥ 9 cycles, n = 242
Sex			0.082			0.298
Male	207	497		185	175
Female	71	127		57	67
Age in yr	56.97 ± 9.85	59.91 ± 10.03	< 0.001	57.35 ± 9.31	58.01 ± 9.17	0.418
Depth of tumor invasion			0.568			0.754
T2	1	1		0	0
T3	72	152		60	63
T4	205	471		182	179
Number of positive lymph nodes			0.110			0.756
0	0	4		0	0
1-2	39	111		36	34
3-6	68	155		60	67
≥ 7	171	354		146	141
Type of gastrectomy			0.044			0.903
Proximal	16	36		13	12
Distal	89	154		71	71
Total	173	454		158	159
Vascular invasion			0.852			0.916
Negative	67	154		59	60
Positive	211	470		183	182
Neural invasion			0.156			0.288
Negative	85	211		74	85
Positive	193	403		168	157
Lauren classification			0.664			0.597
Intestinal	52	125		46	42
Diffuse	153	315		127	127
Mixed	73	184		69	73
Maximum diameter of tumor in cm			0.346			0.467
< 6	134	322		119	111
≥ 6	144	302		123	131
Surgical margin			0.571			0.254
Negative	260	577		225	218
Positive	18	47		17	24

PSM: Propensity score matching.

Table 5 Subgroup analysis of overall survival by Cox regression analysis of stage III gastric cancer patients

Variables	Death	Total	HR	95%CI	P value	P for interaction
Sex						0.639
Male	198	360	1.258	0.951-1.664	0.108
Female	72	124	0.925	0.582-1.470	0.741
Depth of tumor invasion						0.127
T3	43	123	1.044	0.569-1.916	0.888
T4	227	361	1.207	0.929-1.567	0.158
Number of positive lymph nodes						0.007
≤ 6	91	197	1.312	0.867-1.988	0.199
≥ 7	179	287	1.115	0.832-1.496	0.466
Vascular invasion						0.099
Negative	58	119	1.365	0.818-2.277	0.233
Positive	211	365	1.138	0.868-1.492	0.350
Neural invasion						0.059
Negative	73	159	1.389	0.872-2.211	0.166
Positive	197	325	1.114	0.842-1.474	0.451
Lauren classification						0.002
Intestinal	39	88	1.196	0.873-1.640	0.264
Diffuse	168	254	1.184	0.872-1.606	0.280
Mixed	63	142	0.975	0.760-1.250	0.840
Maximum diameter of tumor in cm						< 0.001
< 6	108	230	1.071	0.734-1.563	0.722
≥ 6	162	254	1.240	0.909-1.692	0.174
Type of gastrectomy						0.004
Proximal	13	25	1.175	0.680-2.032	0.564
Distal	65	142	0.915	0.560-1.494	0.722
Total	192	317	1.125	0.976-1.297	0.105

CI: Confidence interval; HR: Hazard ratio.

Table 6 Subgroup analysis of progression-free survival by Cox regression analysis of stage III gastric cancer patients

Variables	Death or recurrence	Total	HR	95%CI	P value	P for interaction
Sex						0.418
Male	227	360	0.925	0.712-1.200	0.555
Female	88	124	0.555	0.363-0.846	0.006
Depth of tumor invasion						0.266
T3	65	123	0.719	0.438-1.181	0.193
T4	250	361	0.813	0.649-1.066	0.145
Number of positive lymph nodes						0.170
≤ 6	108	197	0.933	0.640-1.361	0.719
≥ 7	207	287	0.753	0.572-0.990	0.042
Vascular invasion						0.382
Negative	72	119	0.824	0.518-1.311	0.414
Positive	243	365	0.829	0.644-1.068	0.147
Neural invasion						0.469
Negative	92	159	0.961	0.638-1.449	0.851
Positive	223	325	0.773	0.593-1.007	0.056
Lauren classification						0.083
Intestinal	47	88	0.886	0.498-1.576	0.632
Diffuse	193	254	0.923	0.695-1.227	0.042
Mixed	75	142	0.576	0.365-0.910	0.406
Maximum diameter of tumor in cm						0.236
< 6	132	230	0.765	0.543-1.078	0.126
≥ 6	183	254	0.850	0.636-1.136	0.271
Type of gastrectomy						0.605
Proximal	15	25	0.781	0.282-2.162	0.635
Distal	82	142	0.761	0.490-1.181	0.223
Total	218	317	0.830	0.636-1.083	0.169

CI: Confidence interval; HR: Hazard ratio.