About CARET

Home | About CARET

Links

Rationale for Study

Design

• Eligibility Criteria

• Recruitment

• Intervention

• Follow-up

• Data Collection

Primary Publications

About CARET

CARET was a randomized, double-blind, placebo-controlled trial of the cancer prevention efficacy and safety of a daily combination of 30 mg of ?-carotene and 25,000 IU of retinyl palmitate in 18,314 persons at high risk for lung cancer. We studied two high-risk populations: 4,060 men with extensive occupational exposure to asbestos, and 7,965 men and 6,289 women with at least 20 pack-years of cigarette smoking history. CARET began in 1985 with two pilot studies (Vanguard cohort) and expanded to six sites beginning in 1988 (Efficacy cohort). The design projected active intervention until 1997, encompassing 110,000 person-years of follow-up for the 18,314 randomized participants. The CARET intervention was halted in January 1996, 21 months ahead of schedule, with the twin conclusions for definitive evidence of no benefit and substantial evidence of a harmful effect of the intervention on both lung cancer incidence and total mortality. During the intervention phase of CARET, serum, plasma, whole blood, and lung tissue specimens were collected on participants. These biospecimens make up the CARET Biorepository. The overall results of CARET were presented at a special NCI press conference January 18, 1996, followed by a publication (NEJM 334:1150-5, 1996). Further details about lung cancer were published (JNCI 88:1550-9, 1996) soon after. Lung cancer incidence and cardiovascular disease mortality findings during the first six years of post-intervention follow-up were published in 2004 (JNCI 96:1743-50, 2004).

On June 30, 2005, CARET stopped active follow-up of participants. Passive follow-up to extend cancer and death outcomes through 2013 was conducted via linkages with select cancer registries and the National Death Index (NDI). CARET continues to support the extensive biological repository and ancillary studies that utilize the CARET samples and data.

For further details, see the CARET Protocol (PDF).