Women who are obese tend to have deadlier types of ovarian cancer, perhaps because fat cells make the tumours grow more aggressively, researchers say.

A study of more than 200 ovarian cancer patients suggested obese women were more likely to have the disease recur. They also faced an earlier death than those with an ideal weight.

"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," said Dr. Andrew Li, who led the study at the Cedars-Sinai Medical Center in Los Angeles, Calif.

Excess weight is linked to the development and prognosis in other cancers, such as breast, uterine and colorectal, but its relationship to ovarian cancer isn't as clear.

Li and his colleagues tracked 216 women with epithelial ovarian cancer — the most common type of the disease, accounting for about 90 per cent of cases.

Of the women studied, 35 were obese and 108 had an ideal weight. The remaining women were underweight or overweight.

Obesity affected survival rates, shortened the time before cancer recurred and led to an earlier death in women with advanced disease, the team reports in Monday's online issue of the journal Cancer.

Tumour biology

The results suggest fat tissue releases a hormone or protein that causes ovarian cancer cells to grow more aggressively, Li said.

"This study supports the hypothesis that obesity impacts ovarian cancer mortality by influencing tumour biology," the study's authors concluded.

More research is needed to confirm if obesity can affect the progression of ovarian cancer and to find out how fat may affect tumour growth, they said.

Ovarian cancers are difficult to diagnose and about 70 per cent of patients die within five years of diagnosis, making it one of the most lethal cancers.

The Canadian Cancer Society estimates 2,300 Canadian women will be diagnosed with ovarian cancer this year and 1,600 women will die from the disease.