Physical activity and regular exercise are associated with a reduced risk of many types of cancer and cancer reoccurrence. Exercise is also a safe and effective intervention to counteract the adverse physical and psychological effects of cancer and its treatment.

Did you know?

Insufficient physical activity is a key risk factor contributing to disease burden in Australia _[1].

The 2017-2018 Australian National Health Survey found that less than 45% of adults were active enough, with only 41% of women, 50% of men and few older Australians (25% of women, 31% of men over 65 years old) meeting the national guidelines [2].

In 2017-2018, only 23% of Australian adults (22% of women, 25% of men) met the muscle strength training guidelines of at least 2 days a week [2].

In 2017-2018, only 15% of adults (14% of women, 17% of men) met both the physical activity and muscle strengthening aspects of the guidelines[3].

Almost half (43.7%) of Australian adults aged 18-64 years described their work day as ‘mostly sitting’ [3].

The Cancer Council and Clinical Oncology Society of Australia recognise that exercise has the benefits of reducing side effects with cancer treatments, and lowering the risk of reoccurrence as well as mortality, yet is not routinely prescibed as part of a patient’s routine treatment planm [4].

The Facts

PHYSICAL INACTIVITY AND SITTING TIME:

• Prolonged sitting time is associated with more than 30% higher risk of endometrial and ovarian cancers, and colorectal cancer mortality [5].
• Sitting for 8 or more hours per day was associated with a 22% higher risk of prostate cancer than sitting for less than 8 hours per day [6].
• Australian adults who did not reach national activity guidelines had a 45% higher risk of lung cancer than those who met the recommendations of 150 minutes per week of moderate-intensity physical activity (or 75 minutes of vigorous intensity) [6].
• Sedentary behaviour increases risk of death due to cancer by about 13% [5,7].

CANCER PREVENTION:

• There is strong evidence that physical activity lowers the risk of colon, breast, kidney, endometrial, bladder, esophagus and stomach cancers, with moderate evidence for lung cancer risk reduction [8].

PHYSICAL ACTIVITY BEFORE AND AFTER DIAGNOSIS:

• Being physically active both before and after a cancer diagnosis has survival benefits.
• Sedentary behaviour increases the risk of mortality from colorectal cancer by almost 40% before diagnosis and more than 60% if continued after diagnosis [5].
• The relationship between pre-diagnosis physical activity and survival from breast, colorectal and prostate cancer has been extensively studied.
  Cancer patients who were most physically active before diagnosis had a cancer-specific mortality risk that was 18% lower for breast cancer and 23% lower for colorectal cancer, but not for prostate cancer.
  However, for all cause-mortality, the risk was reduced by 13% for prostate cancer and 25% for colorectal cancer among patients who were most physically active before diagnosis when compared to patients who were least active [7].
• Risk reduction was even greater (26% to 69%) for patients who were most physically active after being diagnosed with breast, colorectal or prostate cancers, compared with patients who were least active [7].
  A 21% to 49% lower risk of mortality for these cancers was found in studies that examined all-cause mortality [7].

SIDE EFFECTS OF CANCER TREATMENT:

1. EXERCISE HAS ADDITIONAL BENEFITS FOR CANCER PATIENTS [9]

2. CANCER-RELATED FATIGUE:

• Exercise delivers significant benefits in reducing cancer-related fatigue [10-12]. Two reviews reported larger effects from exercising during active cancer treatment, rather than after [13,14].
• A recent, large, high-quality systematic review identified exercise (including aerobic, resistance and mixed forms), as the most impactful intervention to reduce cancer-related fatigue when compared to pharmaceutical interventions or psychological interventions alone [15].

3. PHYSICAL FITNESS:

• Exercise interventions have demonstrated a strong positive impact on physical fitness measures, including: aerobic exercise tolerance [16,17], peak power [18], strength [10], flexibility [19] and various measures of cardiorespiratory fitness 20,21]. These trials included aerobic, resistance and mixed forms of exercise interventions with most positive outcomes and larger effects associated with moderate to vigorous exercise intensity.

4. PSYCHOLOGICAL FUNCTION:

• Most studies so far have demonstrated a positive impact of exercise on psychological function, including mood, depression and anxiety [10,18,19,22].

5. PHYSICAL FUNCTION:

• Therapeutic exercise interventions are also beneficial when targeting the  restoration of function in specific body regions, including flexibility and progressive resistive exercises for the upper extremities [23,24] and pelvic floor strengthening [25].

6. QUALITY OF LIFE:

• A large systematic review indicated that exercise may have beneficial effects on health-related quality of life. These positive effects are greater with moderate‐ or vigorous‐intensity than mild‐intensity exercise programs [26].

7. TOLERATING TREATMENT:

• Physical activity can help cancer patients tolerate aggressive treatments and experience fewer and milder adverse effects [27]

8. BIOMARKERS ASSOCIATED WITH CANCER PROGRESSION:

• Exercise positively impacted the immune system and inflammatory biomarkers of cancer patients, both during and after cancer treatment [28]. The most positive outcomes were found in interventions that used moderate or vigorous exercise [18,29].

9. ADDITIONAL BENEFITS:

• Cancer survivors who were physically active had better glucose control, better insulin and CRP levels, and improved insulin sensitivity [30].

DOSAGE:

• Exercise dosage is important. For example, in studies examining the risk of breast cancer, significant reductions in risk occurred with 120 to 360 minutes per week of moderate intensity exercise (or 75 to 230 minutes per week of vigorous intensity exercise) [31].
• Similarly, studies examining the association between breast cancer mortality and post-diagnosis physical activity/exercise reported benefits when activity ranged from 120 to 250 minutes per week of moderate intensity exercise (or 75 to 150 minutes per week of vigorous intensity exercise) [32].

SAFETY:

• In general, exercise interventions at moderate and vigorous intensity are safe in supervised settings with few adverse effects [10,33].
• For cancer patients who lack the physical conditioning to engage in more intense exercise, low intensity exercise can still improve overall physical function and reduce cancer-related fatigue, anxiety and depression [9].

TIMING:

• While exercise performed at all stages of treatment will provide benefits, the benefit to specific cancer-related impairments will vary depending on the type and timing of exercise. For example, starting regular exercise once treatment is completed had greater impact on quality of life, physical function and upper and lower body strength, while exercise initiated during treatment had a greater impact on cancer-related fatigue [9].

BARRIERS AND FACILITATORS:

• A study of prostate-cancer patients identified different barriers and facilitators to lifestyle change [34].
  
  

BARRIERS INCLUDED:

• Unclear scientific guidelines, perceived lack of evidence for the benefits of change or a link between the lifestyle factor and the specific cancer
• Side effects of treatment
• Belief that lifestyle changes are unnecessary as they are already healthy
• Time pressure
• Too old to make a change.
  
  

FACILITATORS INCLUDED:

• Cancer diagnosis
• Recommendation for change by an exercise physiologist or other healthcare professional  
• Supportive family, friends and group-based programs
• The desire to try new coping strategies to manage side effects and improve physical and mental well‐being.

What can we do about it

TO PREVENT CANCER:

• Reduce sitting time
• Adopt a physically active lifestyle, engaging in at least 30 minutes of moderate to vigorous physical activity on five or more days of the week.
• The current physical activity guidelines recommend 150 to 300 minutes per week of moderate-intensity physical activity (or 75 to 150 minutes per week of vigorous-intensity aerobic activity), although the precise amount needed for reduced risk of cancer is still uncertain [7].

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FOR CANCER PATIENTS [35]:

Although generally safe, patients should be screened and appropriate precautions taken.

Individuals diagnosed with cancer should return to normal daily physical activity (as much as their current abilities and conditions allow) as soon as possible after diagnosis, aiming to build up to and maintain participation in:

• at least 150 minutes per week of moderate intensity (e.g. walking) or 75 minutes of vigorous intensity aerobic exercise (eg, jogging, cycling, swimming); and two to three sessions per week of moderate to vigorous intensity resistance exercises (e.g. lifting weights) that target the major muscle groups.
• The specific exercise patients should engage in will depend on their individual ability and health status, therefore should be adapted to the anticipated disease trajectory and adverse effects related to their specific cancer and treatment.
  
  

Exercise programs should be designed around the individual’s specific needs and abilities by an accredited exercise physiologist or physiotherapist.

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