The Effects of Equivalent Weight Loss With or Without Exercise Training on Breast Cancer Risk (SHAPE-2)
Condition: Breast Cancer Risk
MeSH terms: Breast Neoplasms; Weight Loss
Study type: Interventional

Summary: 
      Physical inactivity and overweight are two accepted risk factors for breast cancer. However,
      because of their correlation it is not clear which is most relevant to risk. The
      investigators now set out to study whether physical activity in addition to weight loss by
      diet only, affects sex hormone levels, known to be related to breast cancer risk.

      In the SHAPE-2 study 250 healthy overweight/obese and physically inactive women are randomly
      allocated to a diet-induced weight loss group, a combined exercise- and diet-induced weight
      loss group or a control group. The aim of the first two intervention groups is to loose 5-6
      kg of bodyweight, either by dieting or mainly by increased physical activity. Measurements
      are performed at baseline and after 21 weeks, the end of the study period.

      The aim of this study is to provide insight into the effect of weight loss mainly driven by
      exercise compared to equivalent weight loss due to nutritional calorie restriction on breast
      cancer biomarkers.
    

Detailed description: 
      Postmenopausal women who are sedentary or overweight, have an increased breast cancer risk.
      It is suggested that these two factors mediate breast cancer risk mainly through sex
      hormone-related pathways. However, an inactive lifestyle and obesity are highly correlated
      and it is not clear which is most relevant to risk.

      Literature shows that weight loss/ fat loss reduces postmenopausal sex hormone levels, but
      the question is if there is an additional beneficial effect on hormones of reaching this
      weight loss by physical activity instead of nutritional interventions.

      In this three-armed, two-center intervention study, 250 sedentary postmenopausal women who
      are aged 50-69 years will first enter a run-in period of 5 weeks. During this period, all
      participants get a diet, adapted to the guidelines for healthy nutrition, meeting their
      energy expenditures to maintain stable weight. After this run-in phase they are randomly
      allocated to a (1) diet induced weight loss group, (2) a combined exercise and diet induced
      weight loss group or (3) a control group. Participants allocated to the dietgroup will get a
      calorie restricted diet of -500 kCal/day, they will remain their habitual exercise pattern.
      Participants in the combined group will follow an exercise programme (combined endurance and
      strength) of 4 hours of sports per week with an average energy expenditure of 350 kCal/day
      and a, less strict. And a calorie restricted diet of -250 kCal/day. The aim of both
      intervention groups is to loose 5-6 kg of body weight during the 14 week intervention period.
      Participants in the control group are requested to retain the baseline diet and their
      habitual exercise pattern. Primary study parameters measured at baseline and after 21 weeks
      are: serum concentrations of endogenous estrogens, endogenous androgens and sex hormone
      binding globulin. Other study parameters include: body fat distribution, amount of total and
      abdominal fat, weight, BMI, physical fitness, blood pressure and lifestyle factors.

      The aim of this study is to provide insight into the effect of weight loss mainly driven by
      exercise compared to equivalent weight loss due to nutritional calorie restriction on breast
      cancer biomarkers. Furthermore, we are specifically interested whether weight loss mainly due
      to physical exercise induces greater amounts of fat loss (total and abdominal) and
      subsequently results in more favourable effects on these hormones compared to equivalent
      diet-induced weight loss.
    

Intervention name(s): Diet; Mainly exercise induced weight loss
Intervention type(s): Behavioral; Behavioral
Intervention description(s): Energy restricted diet, according the national guidelines for healthy nutrition, creating a mean energy deficit of 500 kCal/day.; Exercise programme of 2 hours per week fitness containing endurance and resistance training. And 2 hours of Nordic Walking. Equivalent to an energy expenditure of 350 kCal/day.
Next to the exercise programme participants will follow an energy restricted diet according to the national guidelines of healthy nutrition creating an extra energy deficit of 250 kCal/day.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Basic Science
Keywords: Breast cancer; Sex hormones; Physical activity