Survival benefits and disparities in radiation therapy for elderly patients with pancreatic ductal adenocarcinoma

Table 1 Baseline demographic and clinical characteristics of elderly patients with pancreatic ductal adenocarcinoma between 2004 and 2018 from Surveillance, Epidemiology, and End Results database before and after propensity score matching

Variables	Subgroups	Before propensity score matching, n (%) of patients (n = 12245)			After propensity score matching, n (%) of patients (n = 4500)
		RT	Non-RT	P value	RT	Non-RT	P value
All parents		9694 (79.2)	2551 (20.8)		2250 (50)	2250 (50)
Age (yr)	65-80	2160 (84.7)	7423 (76.6)	< 0.001	1884 (83.7)	1857 (82.5)	0.301
	> 80	391 (15.3)	2271 (23.4)		366 (16.3)	393 (17.5)
Year of diagnosis	2004-2010	1329 (52.1)	5195 (53.6)	0.186	1185 (52.7)	1184 (52.6)	1.00
	2011-2018	1222 (47.9)	4499 (46.4)		1065 (47.3)	1066 (47.4)
Sex	Female	1166 (45.7)	3203 (33.0)	< 0.001	898 (39.9)	875 (38.9)	0.502
	Male	1385 (54.3)	6491 (67.0)		1352 (60.1)	1375 (61.1)
Race	White	2021 (79.2)	7687 (79.3)	0.713	1784 (79.3)	1789 (79.5)	0.916
	Black	249 (9.8)	983 (10.1)		218 (9.7)	210 (9.3)
	Other	281 (11.0)	1024 (10.6)		248 (11.0)	251 (11.2)
Marital status	Married	1586 (62.2)	5384 (55.5)	< 0.001	1377 (61.2)	1359 (60.4)	0.604
	Unmarried	965 (37.8)	4310 (44.5)		873 (38.8)	891 (39.6)
Primary site	Head	1737 (68.1)	5414 (55.8)	< 0.001	1509 (67.1)	1536 (68.3)	0.635
	Body/tail	503 (19.7)	2739 (28.3)		452 (20.1)	428 (19.0)
	Other	311 (12.2)	1541 (15.9)		289 (12.8)	286 (12.7)
Histology grade	Grade I-II	692 (27.1)	1882 (19.4)	< 0.001	579 (25.7)	578 (25.7)	0.952
	Grade III-IV	472 (18.5)	1344 (13.9)		406 (18.0)	414 (18.4)
	Unknow	1387 (54.4)	6468 (66.7)		1265 (56.2)	1258 (55.9)
Node status	Negative	1457 (57.1)	6047 (62.4)	< 0.001	1295 (57.6)	1328 (59.0)	0.333
	Positive	1094 (42.9)	3647 (37.6)		955 (42.4)	922 (41.0)
Tumor size (cm)	< 2	229 (9.0)	909 (9.4)	< 0.001	195 (8.7)	207 (9.2)	0.821
	2-4	1491 (58.4)	5076 (52.4)		1317 (58.5)	1310 (58.2)
	> 4	831 (32.6)	3709 (38.3)		738 (32.8)	733 (32.6)
SEER stage	Localized	320 (12.5)	1019 (10.5)	< 0.001	285 (12.7)	306 (13.6)	0.606
	Regional	1813 (71.1)	3726 (38.4)		1547 (68.8)	1540 (68.4)
	Distant	418 (16.4%)	4949 (51.1)		418 (18.6)	404 (18.0)
Surgery	No	1592 (62.4)	7622 (78.6)	< 0.001	1439 (64.0)	1466 (65.2)	0.418
	Yes	959 (37.6)	2072 (21.4)		811 (36.0)	784 (34.8)
Chemotherapy	No	297 (11.6)	4304 (44.4)	< 0.001	297 (13.2)	310 (13.8)	0.601
	Yes	2254 (88.4)	5390 (55.6)		1953 (86.8)	1940 (86.2)

RT: Radiation therapy; SEER: Surveillance, Epidemiology, and End Results.