The findings, published in the October 1 2006 issue of Cancer, a peer-reviewed journal of the American Cancer Society, place even more pressure on a food industry already struggling to cope with the growing epidemic.
The new study provides evidence that obesity leads to more aggressive types of ovarian cancer, after researchers found significant differences in histological types of epithelial ovarian cancer depending on body mass index (BMI). In addition, for women with advanced disease, a higher BMI was associated with decreasing survival rates, says the study.
Obesity has been linked to an increased risk of bowel, kidney, oesophageal and stomach cancers, as well as womb and breast cancer in post-menopausal women. But its relationship with ovarian cancer is less well understood.
Almost one in 60 women are estimated to develop ovarian cancer during their lifetimes. Most will be diagnosed with advanced disease and 70 percent will die in five years, making it one of the most lethal cancers. There are several types of ovarian cancer, but tumors that begin from surface cells of the ovary (epithelial cells) are the most common type.
Recent studies have shown that obese patients have a worse outcome. Scientists hypothesize that higher mortality associated with obesity may be caused by more aggressive tumors rather than delays in diagnosis.
In the new study, Andrew Li of the Cedars-Sinai Medical Center and Women's Cancer Research Institute at the Samuel Oschin Comprehensive Cancer Institute and colleagues reviewed data from 216 women with ovarian cancer to identify relationships between obesity, ovarian cancer and tumor biology.
"Comparison of obese (35 of 216) and ideal weight (108 of 216) women showed 29 percent of obese women and 10 percent of ideal weight women had localized disease. However, obesity was significantly associated with both different cellular characteristics of the tumor and outcome in women with advanced disease," wrote the researchers.
According to the study, obese women were more likely to have mucinous types of tumors and tended to have non-serous types as well.
"This study supports the hypothesis that obesity impacts ovarian cancer mortality by influencing tumor biology," concluded the authors. Additionally, the researchers observed "significant differences in the risk of cancer progression and cancer-related mortality associated with increasing BMI in a fairly 'dose-dependent' fashion."
Indeed, last year, a number of academic studies presented at the AACR International Conference on Frontiers in Cancer Prevention Research revealed growing evidence that overall cancer incidence and mortality resulting from overweight and obesity is increasing.
Obesity is currently thought to affect more than 64 percent of the US's adult population and 16 percent of children, and has been repeatedly linked with an increased risk of other health conditions such as heart disease and diabetes.
A report published in The Lancet in November (vol 366, no 9499), estimated that 35 per cent of the 7 million deaths from cancer in 2001 were caused by a lifestyle that could have been changed, and drew attention to nine modifyable risk factors.
In this instance, the researchers from Harvard University based their findings on a comprehensive review of scientific studies and other sources such as government reports.