Two strengths of our study were that while most other studies of this type have used self-reported weight and height to calculate BMI, we directly measured these in all of our participants. Unlike most other studies, we also directly measured fat mass, Chionh said. This approach makes the measurements more reliable.
Scientists have evidence that regular exercise protects against bowel and breast cancers, and possibly endometrial and prostate cancers, but it has also been difficult to ascertain the influence of exercise on other types of cancer, Chionh said.
This is probably due to measurement error when estimating levels of physical activity and exercise, she said. We believe the methods we used help bring us closer to the truth about risk factors for ovarian cancer, but further study is still needed to determine if there is a real causal relationship between exercise and an increased risk.
Several hypotheses support the biological plausibility of an increased ovarian cancer risk with higher levels of physical activity, Chionh said.
Some studies have shown that higher levels of physical activity are linked with decreased oestrogen levels in women. This may trigger the pituitary gland to release more gonadotropin hormones, which have been theorised to lead to possible development of ovarian cancer by stimulating oestrogen or oestrogen precursors that cause excessive proliferation of ovarian cells.
Another study has shown that higher levels of physical activity are linked with increased androgen levels, which have also been hypothesised to play a role in ovarian cancer development.
A third hypothesis is linked with a study showing that higher levels of vigorous exercise lea
|Contact: Emma Ross|
ECCO-the European CanCer Conference