Opportunities and challenges in incorporating ancillary studies into a cancer prevention randomized clinical trial

Table 3 Timing of registration to ancillary study and randomization to SELECT

	Years between randomization and registration to ancillary study (number of men)^a
	0^b	1	2	3	4	5	6	7	Post SELECT unblinding
PREADVISE	2095	2216	952	185	428	815	416	110	267
SEE	0	68	182	355	535	424	290	67	510
RAS	141	489	1125	1157	7	1	0	0	0
ACP	0	0	0	0	15	75	100	96	7642

^aPrior to study unblinding and cessation of supplementation
^bWithin 45 days of randomization
ACP Adenomatous Colorectal Polyps study, PREADVISE Prevention of Alzheimer’s Disease with Vitamin E and Selenium, RAS Respiratory Ancillary Study, SEE SELECT Eye Endpoint study

ISSN: 1745-6215