Exercise and Metformin in Colorectal and Breast Cancer Survivors

• Compare changes in other insulin-related biomarkers [ Time Frame: 3 years ] [ Designated as safety issue: No ]
  Markers related to insulin and insulin-like growth factors (including C peptide, insulin-like growth factor 1 [IGF-1], IGF binding protein-3 [IGFBP-3], adiponectin, lectin) will be measured by a blood draw at baseline, 3 months and 6 months
• Explore for an interaction effect in addition to an additive effect of exercise and metformin in reducing fasting insulin level over the 3 month intervention [ Time Frame: 3 years ] [ Designated as safety issue: No ]
• Compare changes in body composition by treatment arm [ Time Frame: 3 years ] [ Designated as safety issue: No ]
  Measures will include body mass index (BMI) at baseline and 3 months
• Compare change in pro-inflammatory markers potentially related to insulin resistance by treatment arm [ Time Frame: 3 years ] [ Designated as safety issue: No ]
  Inflammatory markers measured in blood at baseline, 3 months and 6 months
• Compare self-directed change in diet quality by treatment arm [ Time Frame: 3 years ] [ Designated as safety issue: No ]
  Participants will complete a food frequency questionnaire at baseline and 3 months

• Compare changes in other insulin-related biomarkers [ Time Frame: 3 years ] [ Designated as safety issue: No ]
  Markers related to insulin and insulin-like growth factors (including C peptide, insulin-like growth factor 1 [IGF-1], IGF binding protein-3 [IGFBP-3], adiponectin, lectin) will be measured by a blood draw at baseline, 6 months and 12 months
• Explore for an interaction effect in addition to an additive effect of exercise and metformin in reducing fasting insulin level over the 6 month intervention [ Time Frame: 3 years ] [ Designated as safety issue: No ]
• Compare changes in body composition by treatment arm [ Time Frame: 3 years ] [ Designated as safety issue: No ]
  Measures will include body mass index (BMI) and dual xray absorptiometry (DEXA) at baseline and 6 months
• Compare change in pro-inflammatory markers potentially related to insulin resistance by treatment arm [ Time Frame: 3 years ] [ Designated as safety issue: No ]
  Inflammatory markers measured in blood at baseline, 6 months and 12 months
• Compare self-directed change in diet quality by treatment arm [ Time Frame: 3 years ] [ Designated as safety issue: No ]
  Participants will complete a food frequency questionnaire at baseline and 6 months

Metformin is a medication that is commonly used in the treatment of diabetes. Recently small studies in cancer patients without diabetes suggest that metformin may benefit in lowering insulin levels. In those studies of patients with cancer but not diabetes, glucose (or sugar) levels in the blood are generally no lowered. Insulin and insulin-like growth factors affect the growth of cancer cells.

This randomized study will compare different interventions; exercise, exercise and metformin, metformin alone, or a control arm. The investigators are not directly testing how either exercise or metformin affects your disease. The investigators are testing how they affect insulin levels in your body as well as other blood markers. The investigators believe that these blood tests may either be related to cancer recurrences or be an early sign of cancer recurrences and they are testing how both exercise and metformin may change those markers.

Subjects will be randomized into one of four groups: exercise training, exercise training and metformin, metformin alone, or control arm. All subjects will have lifestyle measurements, interviews regarding activity level, diet questionnaires, and blood tests.

Subjects randomized to exercise training will participate in two supervised exercise sessions per week with an exercise physiologist for 3 months. They will also be asked to exercise on their own for up to an additional 120 minutes each week.

Subjects randomized to exercise training and metformin will participate in two supervised exercise sessions per week and will take metformin. Metformin will be taken once daily for the first two weeks and then twice daily for 3 months.

Subjects randomized to metformin will take metformin once daily for the first two weeks and then twice daily.

Subjects on the control arm will receive a packet of educational information on nutrition and physical activity developed by the National Cancer Institute and American Cancer Society. In addition to education information, they will be offered two supervised sessions with an exercise physiologist as well as a pedometer 3 months after enrollment in the study.

• Colorectal Cancer
• Breast Cancer

• Behavioral: Exercise training
  Two supervised exercise sessions per week
• Drug: Exercise training plus metformin
  Two supervised exercise sessions per week. Oral metformin QD for 2 weeks, then BID
• Drug: Metformin
  Oral metformin QD for two weeks, then BID
• Other: Educational information
  educational information

• Active Comparator: Exercise training
  Exercise training with exercise physiologist
  Intervention: Behavioral: Exercise training
• Active Comparator: Exercise training with metformin
  Exercise training with exercise physiologist with oral metformin
  Intervention: Drug: Exercise training plus metformin
• Active Comparator: Metformin
  Metformin
  Intervention: Drug: Metformin
• Active Comparator: Control
  Educational information
  Intervention: Other: Educational information

Inclusion Criteria:

• Histologically confirmed stage I-III colorectal or breast cancer
• Undergone curative-intent complete surgical resection and completed all adjuvant therapy (if indicated) at least 2 months prior to enrollment
• Note: Breast cancer subjects on hormonal therapy or trastuzumab only therapy and colorectal cancer subjects on adjunctive therapies not considered cytotoxic chemotherapy (including those participating in CALGB 80702 receiving only celocoxib/placebo) are eligible.
• Participants will be allowed to receive concomitant adjuvant endocrine therapy for breast cancer; however, all endocrine agents must be initiated at least 1 month prior to enrollment in the study and continued throughout the duration of study participation.
• Less than 120 minutes of exercise per week
• Approval by oncologist or surgeon
• English speaking and able to read English
• No planned surgery anticipated in the 3 month intervention period
• At least one month from any major surgery to start of intervention including colostomy reversal

Exclusion Criteria:

• Concurrent other malignancy or history of other malignancy treated within the past 3 years (other than non-melanoma skin cancer or in-situ cervical cancer)
• Metastatic disease
• Scheduled to receive any form of further adjuvant cancer therapy
• Currently on medication for diabetes treatment
• Pregnant or breast-feeding
• Any condition associated with increased risk of metformin-associated lactic acidosis (prior renal failure or liver failure, history of acidosis of any type; habitual intake of 3 or more alcoholic beverages per day)
• Known hypersensitivity or intolerance to metformin