Breast cancer survivors are often vigilant about follow-up testing to keep an eye out for recurrence. But new research suggests the need for vigilance with the scale as well.

Pooling data from three national studies, researchers looked at long-term outcomes of more than 6,800 women with breast cancer. They wanted to find out if their weight had any impact on whether the cancer returned.

The researchers found that increasing body mass index significantly increased women's risk of cancer recurrence and death, even if they did well with treatment. The weight connection was only seen in women with hormone-receptive positive breast cancer, the most common type of breast cancer which accounts for more than two-thirds of all breast cancer cases.

Further study is needed to determine if weight loss can make a difference after breast cancer diagnosis. The research team believes that treatment strategies aimed at interfering with hormonal changes and inflammation caused by obesity may help reduce the risk of recurrence.