Exercise Physiology and Cancer

Prevalence of Cancer

  • Cancer is prevalent, with roughly 1 in 50 people affected in 2022.
  • Men are slightly more likely to be diagnosed.
  • Approximately 3 in 10 deaths in Australia result from cancer.
  • Lifetime likelihood of being affected by cancer personally or through someone known.

Pathophysiology of Cancer

  • Definition: Uncontrolled division of abnormal cells.
  • Over 100 types of cancer, categorized into:
    • Carcinomas: Epithelial lining of organs.
    • Sarcomas: Bone and connective tissue.
    • Lymphoma: Lymphatic system.
    • Leukemia: Blood cells.
  • Underlying contributors:
    • Sedentary lifestyle: Increases risk.
    • Genetics: Uncontrollable.
    • Lifestyle factors: Alcohol, smoking, diet, obesity (controllable).

Tumor Development Stages

  • Stage 1: Localized in a small area.
  • Stage 2: Increased in size.
  • Stage 3: Spread to other parts of the body.
  • Stage 4: Grown and spread to most parts of the body.
  • Early detection is key.

Breast and Lung Cancer Prevalence

  • Among the most common cancer forms worldwide.
  • Exercise and Risk Reduction:
    • Breast Cancer: Strong evidence, 12-21% relative risk reduction with a dose-response relationship.
    • Lung Cancer: Moderate evidence, approximately 25% relative risk reduction with a dose-response relationship.

Benefits of Exercise for Breast Cancer Patients (Post-Diagnosis)

  • Improvements observed during chemotherapy, radiation, post-operation, and long-term.
  • Exercise Capacity and Cardiac Function:
    • Active leisure time physical activity maintains exercise capacity and left ventricular ejection fraction (LVEF).
    • Insufficient physical activity leads to significant reductions in exercise capacity and LVEF (p < 0.05).
    • Leisure time activity reduces treatment-induced cardiac dysfunction.
  • Long-Term Perspective (Survival Rate):
    • Exercise improves prognosis and survival rate.
    • Factors contributing to improved survival:
      • Increased immune function.
      • Decreased estrogen and GF levels.
      • Increased insulin sensitivity.
      • Improved psychological/cognitive health, mood, and quality of life.

Cancer-Related Fatigue (CRF)

  • Aerobic exercise significantly reduces CRF.
  • Resistance training, as tolerated, also reduces CRF, but aerobic exercise is slightly more beneficial.

Exercise and Lung Cancer (Post-Diagnosis)

  • Exercise training depends on the type of therapy (pre/post lung resection or inoperable disease).
  • Pre-Lung Resection:
    • Aerobic and resistance exercise improve exercise capacity.
    • Reduces postoperative complications, hospital stay, and intercostal catheter duration.
  • Post-Lung Resection:
    • Aerobic plus resistance training improves exercise capacity, quality of life, and muscular strength.
    • Reduces dyspnea.
  • Inoperable Disease:
    • Exercise maintains or improves exercise capacity and quality of life.

Mechanisms of Benefit with Exercise for Lung Cancer

  • Reduction in fatigue and no exacerbation of fatigue levels.
  • Lung function improvements (FEV1, forced vital capacity, respiratory muscle strength).
  • Improvement in mood state, quality of life, decrease in anxiety/depression, and increase in sleep quality.
  • Biological Perspective:
    • Increase in VEGF (vascular endothelial growth factor).
    • Increase in chemo tropic delivery.
    • Decrease in hypoxia.
    • Increase in immunomodulation (natural killer cells, interleukin-1).
    • Reduction in cancer cell proliferation.

Limitations of Exercise Post-Lung Cancer Surgery

  • Lobectomy (removal of one lobe):
    • Disproportionate early loss of lung function, but significant improvement over time.
    • Approximately 13% functional loss in exercise capacity.
  • Pneumectomy (removal of entire lung):
    • Larger loss in lung function, typically sustained without improvement.
    • Approximately 28% functional loss in exercise capacity, with dyspnea as the main limiting factor.

Functional Loss After Lung Cancer Surgery

  • FEV1: Significant loss post-surgery, maintained over time.
  • Vital Capacity: Significant reduction, with improvement in lobectomy cases.
  • Maximal Oxygen Consumption: Significant reduction, trend towards increase.
  • Maximal Workload: Similar upward trends post-op.

FIT Recommendations for Cancer

  • Dependent on the type of cancer.
  • American College of Sports Medicine (ACSM) provides guidelines for health-related outcomes.
  • Considerations for aerobic, resistance, or combined exercise doses.
  • Outcomes include cancer-related fatigue, quality of life, physical function, anxiety, depression, lymphedema, bone health, and sleep quality.