Effect of Exercise on Biomarkers of Colon Cancer Risk
Condition: Colon Cancer Prevention
MeSH terms: Colonic Neoplasms
Study type: Interventional
Phase: Phase 2/Phase 3

Summary: 
      There is strong observational epidemiologic evidence that physical activity is inversely
      associated with risk of colon cancer occurrence in both men and women. This association has
      been found in over 30 observational studies, and appears to be independent of effects of
      diet, body fat mass, and other potential confounding factors. Prior to large-scale
      recommendations regarding exercise as a means of preventing colon cancer, however, more
      information is needed regarding the type of exercise, when it must be initiated, and how much
      must be done, in order to produce a protective effect. Information on the mechanisms and
      biological pathways through which exercise might protect the colon will aid in developing the
      answers to these questions.

      This is a randomized controlled trial of a one-year moderate/vigorous exercise intervention
      vs. delayed- exercise control on various biomarkers of colon cancer risk in persons that have
      undergone a colonoscopy within the past 36 months.. The trial is designed to establish the
      effects of the exercise intervention on colorectal cell proliferation and terminal
      differentiation, and on factors that may lie in the pathway between exercise and
      proliferation and apoptosis, in colon and rectal epithelium. It will provide data on: 1) the
      efficacy of a one-year moderate intensity aerobic exercise program in modulating these
      processes to a pattern considered low risk for colon cancer, and 2) the mechanisms whereby
      exercise may lower colon cancer risk in humans. To the investigators' knowledge, this will be
      the first study of its kind.
    

Detailed description: 
      The specific aims of the proposed study are:

        1. To measure the effects of a one-year moderate/vigorous intensity aerobic exercise
           program vs. a delayed-exercise control program in persons that have undergone a
           colonoscopy within the past 36 months on proliferation rate in the upper part of colon
           and rectal mucosa crypts.

        2. To also measure the effects of a one-year moderate/vigorous intensity aerobic exercise
           program vs. delayed-exercise control program in persons that have undergone a
           colonoscopy within the past 36 months on:

             -  expression of apoptosis-related proteins (bax/bcl-2 ratio) in colon and rectal
                mucosal biopsies

             -  rectal mucosal prostaglandin levels

             -  fasting serum/plasma insulin, glucose, triglycerides, insulin-like growth factor
                1(IGF-1), and IGF binding protein-3 (IGFPB-3)

             -  body fat mass and distribution (body mass index, waist and hip circumferences,
                bioelectrical impedance, DEXA scan)

             -  subcutaneous abdominal and intra-abdominal fat mass (measured by one-slice CT scan
                at the L4 level)

             -  fitness (VO2max)

             -  quality of life (measured by standardized self-report instruments)

             -  sleep quality
    

Intervention name(s): Exercise
Intervention type(s): Behavioral
Intervention description(s): 60 minutes/session of aerobic exercise, 6 d/week at 50-50% HHR. All sessions will begin with 10 minutes of stretching and 5 minutes of warm-up, and will end with 5 minutes of cool down.
Allocation: Randomized
Intervention model: Single Group Assignment
Masking: Single (Investigator)
Primary purpose: Prevention