Change in Cardiorespiratory Fitness and Breast Cancer Incidence and Mortality
Study Details
Study Description
Brief Summary
The aim of this observational study is to investigate the association between mid-life changes in cardiorespiratory fitness and the risk of breast cancer incidence and mortality among Swedish women.
The main questions to answer are:
- Are changes in cardiorespiratory fitness associated with the risk of being diagnosed or dying from/with breast cancer later in life?
Participants performed at least two occupational health assessment tests, which consisted of a submaximal ergometer cycle test, measurement of body mass and height to calculate BMI, and a questionnaires on physical and life style habits.
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Detailed Description
PLAN FOR THE STATISTICAL ANALYSES
This plan has been made before any data analysis has been conducted.
The primary statistical analysis aims to determine if there is any association between changes in estimated cardiorespiratory fitness (both absolute L/min and relative ml/min/kg) and breast cancer incidence and mortality.
Cox proportional hazards models will be analysed with inverse probability treatment weights of time-varying confounders such as BMI, physical activity smoking and alcohol. Time stable confounders will be baseline cardiorespiratory fitness, education, co-morbidities. Risk time will be calculated as the time from last cardiorespiratory fitness test to the diagnosis of breast cancer or the end of study. In addition, restricted cubic splines will be performed.
Secondary analysis will be performed to determine if the association remains after dividing into prespecified groups. The first analysis will be conducted by grouping individuals who decrease, stay stable or increase in cardiorespiratory fitness. The second analysis, we will conduct is an analysis to investigate if age (proxy for menopausal status) modifies the relationships between change in cardiorespiratory fitness and breast cancer incidence or mortality. This will be performed in two analyses by splitting on age 50 and 60, respectively. In the third analysis we will investigate if baseline fitness modifies the association. This will be done with fitness both as a continuous and stratified into tertiles.
Proportional hazard assumption was checked using scaled Schönfelts residuals.
Analysis will include four models and include confounders relevant to the outcomes and research questions. These will be as follows:
Model 1: Baseline cardiorespiratory fitness Model 2: Baseline cardiorespiratory fitness, age, education and date of last health assessment test Model 3: Baseline cardiorespiratory fitness, age, education and date of last health assessment test, BMI Model 4: Baseline cardiorespiratory fitness, age, education and date of last health assessment test, BMI, physical activity, smoking and alcohol intake.
Sensitivity analysis: To address potential reverse causality we will exclude individuals who are diagnosed with breast cancer within two years after the last health assessment.
Study Design
Outcome Measures
Primary Outcome Measures
- Incidence of breast cancer [From last health assessment test until 31th of December 2019]
ICD 10, C50 Malignant neuroplasm of breast
- breast cancer specific mortality [From last health assessment test until 31th of December 2019]
ICD 10, C50 Malignant neuroplasm of breast
Eligibility Criteria
Criteria
Inclusion Criteria:
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Older than 18 years
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Performed at least two health assessment tests
Exclusion Criteria:
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Cancer diagnoses prior to the second health assessment test
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Missing data on any exposure or confounder
Contacts and Locations
Locations
No locations specified.Sponsors and Collaborators
- The Swedish School of Sport and Health Sciences
- HPI Health Profile Institute
- Swedish Cancer Society
Investigators
None specified.Study Documents (Full-Text)
None provided.More Information
Publications
None provided.- Dnr 2015/1864-31/2