The influence of obesity on cancer outcomes (IOCO)
Research type
Research Study
Full title
The influence of obesity on cancer outcomes: a prospective cohort study within the United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS)
IRAS ID
260323
Contact name
Elaine Leung
Contact email
Sponsor organisation
University of Glasgow
Duration of Study in the UK
2 years, 0 months, 0 days
Research summary
Obesity increases the risk of developing different cancers, including ovarian cancer. However, existing studies on the relationships between obesity and cancer outcomes demonstrated conflicting results.
Previous systematic reviews and meta-analyses suggested similar or worse survival rates in obese women with ovarian cancer. However, both reviews identified significant inter-study variations, and the majority of studies used body mass index (BMI) at diagnosis as an indicator of obesity, which could be confounded by cancer-related processes. For example, fluid accumulated in the abdomen secondary to advanced intra-abdominal cancer (known as ascites) could be reflected as a falsely high BMI at diagnosis. On the other hand, excessive muscle wasting secondary to advanced cancer (described as cancer cachexia) can lead to rapid decrease in BMI at diagnosis, masking the effects of obesity on cancer progression at the earlier stages of cancer pathogenesis. For patients with advanced disease, higher BMI at diagnosis (i.e. a selected group of patients less affected by cachexia) were previously associated with improved cancer survival.
These observations- known as the obesity paradox in cancer- were previously attributed to the methodological limitations of the existing studies. Studies that can address the limitations of previously published research, including selection bias, confounders (e.g. co-morbidities) and reverse causation, are needed to elucidate the relationships between obesity and cancer outcomes in different cancers.
The aim of this study is to evaluate the influences of obesity on cancer outcomes, including survival, in women participating in the United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS). Using this large cohort, with prospective long-term follow-up and detailed information of their demographics and body weight and height at recruitment, will minimise bias and provide important information to clarify the relationship between obesity and cancer outcomes, and help guide management of obese women with cancers.
REC name
West of Scotland REC 5
REC reference
19/WS/0048
Date of REC Opinion
22 Mar 2019
REC opinion
Favourable Opinion