Are the indications for postoperative radiotherapy in the NCCN guidelines for patients with gastric adenocarcinoma too broad? A study based on the SEER database

Table 1 Demographic and Clinicopathologic Variables of the Development and Validation Cohorts

Variable	Chemoradiotherapy Cohort(n = 7424)		Chemotherapy Cohort(n = 4905)
Variable	No. of Patients	%	No. of Patients	%	χ2test P
Sex					.000
Female	2705	36.4	1805	36.8
Male	4719	63.6	3100	63.2
Race					.000
Black	1033	13.9	606	12.4
Other (American Indian/AK Native, Asian/Pacific Islander)	1628	21.9	1007	20.5
White	4763	64.2	3292	67.1
Age y					.000
≤ 65	4314	58.1	2656	54.1
> 65	3110	41.9	2249	35.9
Depth of invasion					.000
Mucosa/Submucosa	448	6.0	273	5.6
Proper muscle	622	8.4	321	6.5
Subserosa	2877	38.8	1858	37.9
Serosa	2700	36.4	1692	34.5
Adjacent organ invasion	777	10.5	761	15.5
Metastatic LNs, No.					.000
0	1033	13.9	866	17.7
1–2	1883	25.4	1260	25.7
3–6	2047	27.6	1186	24.2
7–15	1855	25.0	1096	22.3
>15	606	8.2	497	10.1
LNs dissection, No.					.000
>15	3474	53.2	2567	47.7
≤ 15	3950	46.8	2338	52.3
Size mm					.000
<55	3670	49.4	2193	44.7
≥ 55	3144	42.3	2038	41.5
Size of tumor cannot be assessed	610	8.2	674	13.7
Primary Site					.000
Proximal third	1590	21.4	1135	23.1
Mid	2256	30.4	1372	28.0
Distal third	2335	31.5	1429	29.1
Stomach, NOS	574	7.7	436	8.9
Overlapping lesion of stomach	669	9.0	533	10.9
Grade
Low	5499	74.1	3632	74.0
High	1672	22.5	1025	20.9
Gx	253	3.4	248	5.1
Histology adenocarcinoma					.751
Other types	6566	88.4	4348	88.6
Intestinal type	858	11.6	557	11.4
AJCC 7th staging					.000
Ib	544	7.3	332	6.8
IIa	673	9.1	559	11.4
IIb	1308	26.7	785	16.0
IIIa	2230	30.0	1358	27.7
IIIb	1883	25.4	1208	24.6
IIIc	786	10.6	663	13.5
Follow-up,month
Median	26		18
Range	0–318		0–319

Abbreviations:LN,lymph node;No.,number; NOS, not otherwise specified;AJCC, American Joint Committee on Cancer;Gx, grade could not be evaluated

ISSN: 1471-2407