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Carotene and Retinol Efficacy Trial (CARET)

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ClinicalTrials.gov Identifier: NCT00712647
Recruitment Status : Completed
First Posted : July 10, 2008
Last Update Posted : September 26, 2012
National Cancer Institute (NCI)
Information provided by:
Fred Hutchinson Cancer Center

Brief Summary:

The Carotene and Retinol Efficacy Trial (CARET) was a randomized, double-blind, placebo-controlled trial of the cancer prevention efficacy and safety of a daily combination of 30 mg of beta-carotene and 25,000 IU of retinyl palmitate in 18,314 persons at high risk for lung cancer. CARET began in 1985, and the 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. CARET continued to follow and collect endpoints on their participants through 2005. During the active intervention phase of CARET, serum, plasma, whole blood, and lung tissue specimens were collected on participants. These biospecimens make up the CARET Biorepository.

The CARET Biorepository is a valuable resource for population-based studies of the major human cancers. During CARET's twenty years of follow-up (1985-2005), we have received reports of 1,445 participants with lung cancer, 901 with prostate cancer, 433 with breast cancer, 334 with bladder cancer, 332 with colon cancer, and 1,429 with other cancers. CARET is one of the few trials that has prospectively collected serum, plasma, whole blood, blood spots (for DNA), and lung cancer tumor specimens, as well as smoking history and serial food frequency questionnaires (in some individuals for up to 12 years) in populations at high risk for lung cancer. This wealth of information in over 18,000 individuals makes the CARET Biorepository a special resource for cancer researchers.

Condition or disease Intervention/treatment Phase
Lung Cancer Drug: Beta Carotene and Retinol Other: Placebo Phase 4

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 18314 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Prevention
Official Title: Caret and Retinol Efficacy Trial: The Caret Coordinating Center
Study Start Date : May 1985
Actual Primary Completion Date : December 2004
Actual Study Completion Date : June 2005

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Vitamin A

Arm Intervention/treatment
Active Comparator: 1
Asbestos-exposed participants and heavy smokers
Drug: Beta Carotene and Retinol

Pilot participants (ppts):

Asbestos-Exposed--15 mg/day beta-carotene + 25,000 IU/day retinol Heavy Smokers--30 mg/day beta-carotene + 25,000 IU/day retinol

Vanguard & Efficacy ppts:

Asbestos-exposed AND heavy smokers--30 mg/day beta-carotene + 25,000 IU/day retinol

Placebo Comparator: 2
Asbestos-exposed participants and heavy smokers
Other: Placebo
Two placebos, one each/day

Primary Outcome Measures :
  1. Lung Cancer Incidence [ Time Frame: bi-annual ]

Secondary Outcome Measures :
  1. Other cancers [ Time Frame: bi-annual ]

Information from the National Library of Medicine

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Ages Eligible for Study:   45 Years to 69 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Asbestos-exposed men who were:

    • current smokers or quit within 15 years prior to enrollment
    • had first exposure to asbestos on the job at least 15 years prior to enrollment
    • had chest X-ray positive for changes compatible with asbestos exposure according to ILO criteria; or had been employed in a protocol-defined high-risk trade for at least 5 years, at least 10 years prior to enrollment.
  • Heavy Smokers, men and women:

    • cigarette smoking history of 20+ pack-years
    • either current smokers or had quit within previous 6 years

Exclusion Criteria:

  • Pre-menopausal women
  • History or cirrhosis or hepatitis within 12 months prior to enrollment
  • Taking > 5500 IU daily vitamin A supplement
  • Taking any beta-carotene supplement
  • History of cancer within 5 years prior to enrollment
  • SGOT > than 2.5X upper limit of normal, or alkaline phosphatase > 1.5X upper limit of normal
  • taking less than 50% of study vitamins during the enrollment period between the First and Second Visits.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00712647

Sponsors and Collaborators
Fred Hutchinson Cancer Center
National Cancer Institute (NCI)
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Principal Investigator: Gary E Goodman, MD Fred Hutchinson Cancer Center
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Responsible Party: Gary Goodman, MD, Fred Hutchinson Cancer Research Center
ClinicalTrials.gov Identifier: NCT00712647    
Other Study ID Numbers: FHCRC IR-4239A
U01CA063673 ( U.S. NIH Grant/Contract )
4239A ( Other Identifier: FHCRC )
First Posted: July 10, 2008    Key Record Dates
Last Update Posted: September 26, 2012
Last Verified: September 2012
Additional relevant MeSH terms:
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Beta Carotene
Vitamin A
Molecular Mechanisms of Pharmacological Action
Protective Agents
Physiological Effects of Drugs