Experts already know obesity
ups the risk of developing some cancers, but
this study suggests fat tissue might also
affect how a tumour progresses.
The authors believe fat cells
excrete a hormone or protein that makes ovarian
cancer cells grow more aggressively.
The Cedars-Sinai Medical
Center research appears in the journal Cancer.
Aggressive tumours
Lead researcher Dr Andrew
Li said: "This study is the first to identify
weight as an independent factor in ovarian
cancer in disease progression and overall
survival, suggesting that there is an element
in the fat tissue itself that influences the
outcome of this disease in obese women."
The researchers looked at
the disease course of 216 women with epithelial
ovarian cancer - the most common type of ovarian
tumours, accounting for 90% of cases.
Comparison of the 35 women
who were obese with the 108 women who were
an ideal weight revealed significant differences
in cancer outcomes.
Obesity influenced survival
rates, shortened the length of time that the
cancer recurred after treatment and led to
earlier death from the cancer.
Dr Li said the next step
would be to examine exactly how fat might
influence tumour growth.
Other studies have found
a compound called insulin-like growth factor
1 (IGF-1) is more highly expressed in obese
people than those who are slimmer and IGF-1
correlates with increased breast cancer risk
in women.
Also, a binding protein for
IGF, called IGFBP-2, seems to promote invasion
in ovarian cancer.
Around 6,800 women are diagnosed
with cancer of the ovary every year in the
UK. It can occur at any age, but is most common
after the menopause.
Ovarian cancers are difficult
to diagnose. Most women will be diagnosed
with late disease and about 70% die within
five years of being diagnosed, making it one
of the most lethal cancers.
Dr Laura-Jane Armstrong,
cancer information officer at Cancer Research
UK, said: "Obesity increases the risk of cancer
of the bowel, womb, gall bladder and oesophagus
cancer, and of breast cancer in post-menopausal
women so it is plausible that it could also
increase a woman's risk of ovarian cancer.
"Indeed, several previous
studies suggested this may be the case.
"However, this current study
involved a relatively small number of patients
so further research is needed to confirm if
obesity can affect ovarian cancer progression.
"Maintaining a healthy weight
is one of the best ways to reduce the chances
of getting cancer."
