Carotene and Retinol Efficacy Trial (CARET)

September 25, 2012 updated by: Fred Hutchinson Cancer Center

Caret and Retinol Efficacy Trial: The Caret Coordinating Center

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.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

18314

Phase

  • Phase 4

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

41 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

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.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / 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

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Lung Cancer Incidence
Time Frame: bi-annual
bi-annual

Secondary Outcome Measures

Outcome Measure
Time Frame
Other cancers
Time Frame: bi-annual
bi-annual

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Fred Hutchinson Cancer Center

Collaborators

National Cancer Institute (NCI)

Investigators

  • Principal Investigator: Gary E Goodman, MD, Fred Hutchinson Cancer Center

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

May 1, 1985

Primary Completion (Actual)

December 1, 2004

Study Completion (Actual)

June 1, 2005

Study Registration Dates

First Submitted

July 8, 2008

First Submitted That Met QC Criteria

July 9, 2008

First Posted (Estimate)

July 10, 2008

Study Record Updates

Last Update Posted (Estimate)

September 26, 2012

Last Update Submitted That Met QC Criteria

September 25, 2012

Last Verified

September 1, 2012

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • FHCRC IR-4239A
  • U01CA063673 (U.S. NIH Grant/Contract)
  • 4239A (Other Identifier: FHCRC)

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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