Body weight is not a factor that has been widely associated with the the risk of developing ovarian cancer. But new research suggests that women who are overweight or obese are more likely to develop the disease, compared with women of a healthy weight.

Investigators from the World Cancer Research Fund (WCRF) and the American Institute for Cancer Research conducted the study as part of the WCRF's Continuous Update Project.

The project monitors and assesses research associated with cancer prevention and uses this information to come to conclusions about how lifestyle factors, such as diet and exercise, may reduce cancer risk.

For other cancers, including breast, bowel and womb cancer, past research has found that being overweight or obese is a risk factor. Now, ovarian cancer can be added to the list, meaning women can make lifestyle changes to reduce their chances of developing the disease.

To reach their findings, the research team reviewed 25 studies involving 4 million women. Of these, 16,000 had ovarian cancer.

The researchers found that for every 5 additional body mass index (BMI) units, there was a 6% increase in the risk of developing ovarian cancer. Furthermore, a non-linear analysis revealed that women with a BMI greater than 28.4 kg/m2 had a significantly higher risk of ovarian cancer than women with a lower BMI.

Commenting on the findings, Dr. Rachel Thompson, head of research interpretation at WCRF, says:

"Previously we only knew about risk factors that are fixed, such as age and family history of the disease, but now we can say that keeping to a healthy weight helps reduce the risk of getting ovarian cancer."

The importance of body weight in cancer risk

According to the Centers for Disease Control and Prevention (CDC), a BMI of 18.5-24.9 is deemed a normal weight for adults aged 20 years or older, while 25-29.9 is classed as overweight and 30 or above is deemed as obese.

Fast facts about ovarian cancer
  • There are expected to be around 21,980 new cases of ovarian cancer diagnosed in the US this year
  • It is the fifth leading cause of cancer related deaths among women
  • Around 50% of women who are diagnosed with ovarian cancer are aged 63 years or older.

Approximately 64% of women in the US are considered to be overweight or obese. These women are at increased risk of 1 in 8 cancers, including breast, bowel, womb, colorectal and now, ovarian cancer.

"These latest findings from the Continuous Update Project show how important body weight is for an increasing number of cancers affecting both men and women," says Dr. Kate Allen, executive director of science and public affairs at WCRF.

In order to maintain a healthy weight, the WCRF says it is important to have BMI checked regularly.

Choosing foods that are lower in energy density, avoiding fast food and sugary drinks, and opting for smaller portion sizes for meals will also help maintain a healthy weight.

Being physically active is also important for a healthy weight, and both diet and exercise has been directly linked to reduced cancer risk.

Medical News Today recently reported on a study finding that postmenopausal women who followed a healthy lifestyle had a 22% lower risk of breast cancer and a 52% lower risk of colorectal cancer.