Physical activity and cancer
14 important questions on Physical activity and cancer
What are the three components of physical activity?
- Frequency
- Intensity
- 1 MET is sitting for 1 hour
- sleep: 0.9 MET
- sedentary behaviours
- 1-1.5 MET
- light intensity activities
- 1.6-2.9 MET
- Moderate intensity activities
- 3-5.9 MET
- Vigorous intensity activities
- >5.9 MET
- Duration
How can PA be measured?
- PA questionnaires
- PA recalls
- PA logs
- PA diaries
Objective methods
- Pedometers
- Accelerometers
- Direct observation
- Physiological measurements
- (GPS)
What is the role of physical activity in the prevention of cancer?
Inactivity ("sedentary time") is associated with increased risk (colon, endometrial, lung, ovarian cancer), independent of physical activity levels
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What are potential mechanisms for physical activity & cancer risk?
- Reduced adiposity
- Decreased oestrogen and androgens
- Decreased insulin and glucose
- Improved immune function
These lead to less cancer
What are the SHAPE studies [example cancer prevention trials]
- Effect of a 1-year exercise intervention on sex hormone level in postmenopausal women (n=189)
- Overall, no favourable effects on sex hormone levels
- But
- in women with >2% body fat loss favourable exercise effect on sex hormone levels
- fat loss was significantly associated with decrease in estrogen levels
- RCTs: effects are largely mediated by weight or fat loss
- decrease body wight or fat >> decrease hormones/breast cancer
Has exercise an additional beneficial effect beyond the effect of weight loss? [SHAPE-2 study]
- effect of equivalent weight loss, with or without exercise, on serum sex hormone levels & inflammatory markers (breast cancer risk)
- three armed RCT
- Mainly exercise group
- Diet group
- Control
- 16-week intervention period
- 50-69
- postmenopausal
- BMI 25-35
- inactive lifestyle
- not smoking
Outcomes and measurements
- primary outcome
- serum sex hormones
- secondary outcome
- inflammation markers
What are the results of the SHAPE-2 study
Total body fat; exercise group lossed more than diet and control group
estradiol; positive reducing in both groups, but no difference between groups [also for free estradiol]
free testosterone; sig. Effect in the exercise group with lowering the free testosterone compaired to diet and control
androstenedione; sig. Effect in the exercise group with lowering the androstenedione compared to control
SHBG; an positive increase in both the diet and exercise group
for the exercise group lower hsCRP and Leptin
Does physical activity improves cancer prognosis?
- PA and survival after breast cancer diagnosis (2005)
- PA and survival after colorectal cancer diagnosis (2006)
Higher PA levels --> decrease in mortality
more evidence also suggest a decreased risk of recurrence and mortality for
- Breast cancer; after diagnosis >> decreased mortality >30%; decreased recurrence 24%
- Colorectal cancer; before and after diagnosis >> decreased mortality 25%
- Prostate cancer; before and after diagnosis >> decreased mortality >49%
What is the history of exercise-oncology
- Advice to rest and avoid exercise
- late 1980s; first (small) exercise study (n=24)
- 1990s; few studies, clinical practice unchanged
- 2000 onwards; increase in # of studies and attention in clinical practice
- 2003; cancer exercise recommendations
What kind of exercise interventions have been studied?
- aerobic exercise
- resistance exercise
- combined aerobic and resistance exercise
Home-based interventions
- walking
- resistance exercises
What are the different aims of exercise interventions
- During treatment
- prevention of side effects
- After treatment
- improvement of fitness, fatigue, QoL
- Mechanistic studies
- effects on blood markers (immune system)
Evidence of exercise; what are the beneficial effect on disease and treatment related side effects
- Cardiorespiratory fitness and muscle strength increases
- Fatigue, sleep disturbances and depression decreases
- Quality of life increases
- Body composition increases
- Inflammation decreases
- Chemotherapy completion rate increases (better toleration)
Although conclusion of meta-analyses are positive, future research needed for:
- Patients with rare types of cancer & patients with advanced disease
- Specific side effects (cognitive complaints, osteoporosis, side-effects from novel targeted therapies)
- Focus on cancer outcomes (progression and survival)
- Focus on optimal frequency, intensity, type, timing of exercise
Physical Activity during Cancer treatment (PACT)-study
- effect of a supervised 18-week exercise program during adjuvant chemotherapy for breast and colon cancer on fatigue
Participants
- Newly diagnosed breast and colon cancer patients
- 25-75 years old
- planned for chemotherapy
Intervention
- 18-week program
- 2 weekly supervised aerobic and resistance training (60min)
- 3 other days for 30min activity
beneficial effect on muscle strength
no effects on quality of life
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