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Carotene and Retinol Efficacy Trial (CARET)

This study has been completed.
National Cancer Institute (NCI)
Information provided by:
Fred Hutchinson Cancer Research Center Identifier:
First received: July 8, 2008
Last updated: September 25, 2012
Last verified: September 2012

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 Intervention Phase
Lung Cancer
Drug: Beta Carotene and Retinol
Other: Placebo
Phase 4

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double Blind (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Prevention
Official Title: Caret and Retinol Efficacy Trial: The Caret Coordinating Center

Resource links provided by NLM:

Further study details as provided by Fred Hutchinson Cancer Research Center:

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

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

Enrollment: 18314
Study Start Date: May 1985
Study Completion Date: June 2005
Primary Completion Date: December 2004 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
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


Ages Eligible for Study:   45 Years to 69 Years   (Adult, Senior)
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.
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Please refer to this study by its identifier: NCT00712647

Sponsors and Collaborators
Fred Hutchinson Cancer Research Center
National Cancer Institute (NCI)
Principal Investigator: Gary E Goodman, MD Fred Hutchinson Cancer Research Center
  More Information

Responsible Party: Gary Goodman, MD, Fred Hutchinson Cancer Research Center Identifier: NCT00712647     History of Changes
Other Study ID Numbers: FHCRC IR-4239A
U01CA063673 ( US NIH Grant/Contract Award Number )
4239A ( Other Identifier: FHCRC )
Study First Received: July 8, 2008
Last Updated: September 25, 2012

Additional relevant MeSH terms:
Vitamin A
Beta Carotene
Retinol palmitate
Growth Substances
Physiological Effects of Drugs
Molecular Mechanisms of Pharmacological Action
Protective Agents
Anticarcinogenic Agents
Antineoplastic Agents processed this record on May 22, 2017