**3. Effects of physical activity on colon and breast cancer survival**

Length of survival after colon cancer or breast cancer diagnosis varies widely, even after accounting for stage at diagnosis and treatment, suggesting other factors may also be important. Lifestyle habit such as physical activity is a modifiable behaviour with multitude of health benefits (Haskell et al., 2007) including beneficial effect on cancer survival. Indeed, several prospective studies have shown that the level of physical activity performed after the diagnosis of cancer significantly decreased overall mortality, cancer mortality and the number of recurrences of cancer.

#### **3.1 Physical activity and breast cancer survival**

112 Topics in Cancer Survivorship

postmenopausal women (HR: 0.81; 95%CI, 0.70-0.93) and -29% for premenopausal women (HR: 0.71; 95%CI, 0.55-0.90) (Lahmann et al., 2007). These results based on a large and heterogeneous cohort (218 169 women from nine European countries, aged 20 to 80 years at baseline followed for an average period of 6.4 years) and which used standardized data collection of physical activity and that could control for all the potential confounding factors, provide additional evidence that moderate forms of physical activity, such as household activity, may be more important than less frequent more intense recreational

Similarly, E3N French study, which is the French part of the EPIC, refers to a decrease in the relative risk of 18% when household activities are of light intensity while this decline is 38% when the activity is of high intensity (Tehard et al., 2006), a dose-response effect being also shown for these household activities. A negative trend in risk of breast cancer associated with total recreational activity (p trend <0.01) and total physical activity (p trend <0.05) was

Moreover, in review of Monninkhof et al. (2007), a trend analysis showed that the risk of developing breast cancer decreased by 6% per hour of physical activity added per week (assuming that the activity would be sustained over a long period of time) showing that this

Overall, the analysis of the literature shows that at least 4 to 7 hours per week of moderate to vigorous physical activity would be required to produce a statistically significant

Several studies have attempted to determine the existence of a period of life in which the protective effects of physical activity would be maximum. In the absence of conclusive studies (pubertal period for some practice, adulthood for others), sustained lifetime physical

**2.3 Summary of the evidence on the protective effects of physical activity on colon** 

colon cancer risk when comparing the most to least active study participants). - at least 4 to 7 hours per week of moderate to vigorous physical activity is required to produce a statistically significant decrease of the risk of breast cancer (reduction of about 25% of breast cancer risk when comparing the most to least active study

**3. Effects of physical activity on colon and breast cancer survival** 


Length of survival after colon cancer or breast cancer diagnosis varies widely, even after accounting for stage at diagnosis and treatment, suggesting other factors may also be important. Lifestyle habit such as physical activity is a modifiable behaviour with multitude of health benefits (Haskell et al., 2007) including beneficial effect on cancer survival. Indeed, several prospective studies have shown that the level of physical activity performed after the diagnosis of cancer significantly decreased overall mortality, cancer mortality and the

activity appears as the most suitable preventive means (Friedenreich et al., 2010).

physical activity in reducing breast cancer risk.

is the total amount of physical activity which is essential.

decrease of the risk of breast cancer.

The available evidence suggest that:

also observed.

**and breast cancer**

participants).

number of recurrences of cancer.

At least seven prospective studies have investigated the relations between physical activity and breast cancer survival (for a review see Barbaric et al., (2010).

The cohort of the Nurses' Health Study (121 700 women followed since 1976) has been the support of the first important study. This study focused on 2987 women with 280 breast cancer deaths and 8 years median follow-up (Holmes et al., 2005). Physical activity was measured by questionnaire every 2 years. The risk of death by breast cancer or breast cancer recurrence was reduced by 20 to 50% among women who walk 3 to 5 h per week (compared to those who walk less than 3 h per week). There was also a reduced risk of breast cancer recurrence and total mortality (Holmes et al., 2005).

The collaborative Women's Longevity Study (CWLS) of 4482 women with breast cancer followed for 6 years with 109 deaths reported a comparable decreased risk of breast cancer death and total death (Holick et al., 2008). These results were confirmed by the Women's Healthy Eating and Living Study (WHEL study) which reported a relative risk of recurrence reduced to 0.56 for women walking 30 minutes a day 6 times per week (Pierce et al., 2007).

Two smaller sized cohorts reported a decreased risk for total mortality but not breast cancer mortality with greater physical activity: the Life after Cancer Eidemiology (LACE) (Sternfeld et al., 2009) and the Health, Eating, Activity and Lifestyle (Heal) study (Irwin et al., 2008).

#### **3.2 Physical activity and colon cancer survival**

Three studies investigated the effects of exercise on cancer survival in patients diagnosed with colon (Meyerhardt et al., 2006a) or colorectal cancer (Haydon et al., 2006;Meyerhardt et al., 2006b).

Meyerhardt et al. (2006a) demonstrated that disease-free colon-cancer survival improved with increasing levels of physical activity (p trend <0.01). Based on the results of this study, it is suggested that a protective HR is observed with >18 total MET-h/wk or equivalent (HR= 0.51; 95% CI: 0.26–0.97, for 18 to 26.9 MET-h/wk); the protective HR does not improve beyond 27 MET-h/wk.

Two studies investigated the effect of physical activity on mortality in patients diagnosed with colorectal cancer. Haydon et al. (2006) demonstrated that persons who exercised at least once a week had improved disease-specific survival (HR = 0.73; 95% CI: 0.54–1.00, p = 0.05). The benefit of physical activity was largely confined to stage II–III tumours (HR = 0.49; 95% CI: 0.30–0.79, p = 0.01), while no association was seen in stage I (least severe) or stage IV (most severe) tumours. The results of the study by Meyerhardt et al. (2006b) supported the role of post-diagnosis physical activity in decreasing cancer-specific mortality (p for trend = 0.008) and overall mortality (p for trend= 0.003) (cohort of the Nurses' Health Study: 573 women whose colon cancer has been diagnosed (stage I, II or III), followed on average 9.6 years). Pre-diagnosis level of physical activity was not found to be predictive of mortality, whereas women who increased their activity level after diagnosis had an HR of 0.48 (95% CI: 0.24–0.97) for colorectal-cancer deaths and an HR of 0.51 (95% CI: 0.30–0.85) for all-cause mortality versus those with no change in activity. In contrast, among women who decreased their activity level there was a modest, though non-significant, increase in both cancerspecific and overall mortality.

All of these studies suggest that physical activity may confer additional benefits to those of the surgery, radiation therapy and/or chemotherapy for survival after treatment of breast or colon cancer. However, these results are observational and cannot formally identify a relationship of cause and effect. However the number of randomized trials

Physical Activity and Cancer: It is Never Too Late to Get Moving! 115

symptoms (fatigue, nausea). Quality of life and sleep quality are also improved with

**of each session**

30 min

20 min

**Frequency per week** 

at least 5 times

3 times

2-3 times

20 min 2 times

physical activity (for a review see Kirshbaum, 2007 and Doyle et al., 2007).

**1) Endurance exercices**  *PA of moderate intensity*  (exemple: brisk walking)

*PA of high intensity* 

*Combination of both* 

endurance

**flexibility** 

**2) Resistance exercises**  for muscle strength and

**3) Stretching exercise for** 


**activity and colon and breast cancer** 

2010;Rogers et al., 2008; Chan & Giovannucci, 2010).

OR

OR

**Type of physical activity Intensity Duration**

Moderate

Vigorous

8-10 exercises

exercise)

Table 1. Recommendations of physical activity (PA: physical activity):

times a week with a duration from 20 to 30 minutes by session.

and brief slow walks should be adopted and slowly advanced.

(with 8-12 repetitions for each

on main muscle groups

There are few recommendations on the type, duration and intensity of physical activity to be practised during the cancer treatment (chemotherapy and/or radiotherapy). In most of the studies, the proposed physical activity was of light to moderate intensity, at the rate of 3 to 5

For people who were sedentary before diagnosis, low-intensity activities such as stretching

Evidence for the underlying mechanisms involved in the pathways between physical activity and cancer is emerging. Numerous biological mechanisms have been proposed and in some cases tested in randomized controlled trials (for a review see (Friedenreich et al.,

In 2007 the World Cancer Research Fund examined associations for physical activity and several cancer types. They concluded that there is a statistical association between excess weight and some cancers including colon cancer and breast cancer in postmenopausal

**6. What biological mechanisms explain the associations between physical** 

testing physical activity interventions for cancer survivors is growing (Pekmezi et al., 2011). Moreover different research have started examining the impact of physical activity on surrogate/biologic markers of survival. All these studies are needed and are still ongoing.

#### **3.3 What type of physical activity is associated with beneficial effect on survival after colon or breast cancer ?**

The review of literature shows that this beneficial effect of physical activity on survival is obtained regardless of the type of training: endurance, strength, or mixed. The intensity from which effects on survival are observed is >9 MET-h/wk which is equivalent to 30 min of brisk walking 5-7 times per week and this regardless of the level of physical activity before the diagnosis.

It is necessary to take into account the state of fatigue of the patients before prescribing a program of physical activity. In all cases, the prescription must be individualized and implemented very gradually. Indeed, "the AP is well tolerated, without adverse effects and oncologists should recommend physical activity to their patients after treatment" (Irwin et al., 2008) (see paragraph 7.2.2).

#### **3.4 Other benefits of physical activity for cancer survivors**

Cancer survivors are not only at increased risk for progressive disease but also a host of comorbid conditions (other cancers, cardiovascular disease, obesity, diabetes and osteoporosis), functional decline and premature death (Demark-Wahnefried et al., 2006a). The impact of exercise is beyond the effects on cancer survival rate as exercise is also associated with other benefits for cancer survivors: exercise is consistently associated with improved quality of life, and also is effective in improving physical functioning (oxygen capacity, cardiorespiratory fitness, other fitness or strength measures, flexibility and global health), anthropometric measures (weight status, body fat, waist circumference) and healthrelated biomarkers (blood pressure, heart rate, circulating hormonal levels) among cancer survivors (Demark-Wahnefried, 2006b).

These effects are obtained with the levels of physical activity recommended for cancer survivors (Haskell et al., 2007) (Table 1).

#### **4. Physical activity recommendations for colon and breast cancer prevention and for cancer survivors**

Physical activity recommendations for colon and breast cancer prevention and after cancer treatment are summarized in table 1.
