Table 3. Patients With Missing Data for at Least 1 Variable.

Variable	Patients with missing data, No. (%)
	Non–small cell lung cancer (n = 1 198 749)	Breast cancer (n = 2 120 775)	Prostate cancer (n = 1 158 635)
Any	851 295 (71.0)	1 161 096 (54.7)	460 167 (39.7)
Demographic	155 917 (13.0)	344 666 (16.3)	161 498 (13.9)
Cancer identification	560 754 (46.8)	284 281 (13.4)	93 111 (8.0)
Cancer stage	420 934 (35.1)	620 313 (29.2)	198 320 (17.1)
Cancer treatment	192 075 (16.0)	408 269 (19.3)	148 644 (12.8)