Being overweight can raise a postmenopausal woman’s risk of breast cancer according to a new study, which finds a link between a higher risk for the disease and a high body mass index (BMI), a measure of body fat based on height and weight.

A new study has found that working the night shift long-term may double a woman’s risk of breast cancer. The association was found in women who did night shift work for 30 or more years. The researcher team led by Kristan Aronson, a professor of public health sciences at the Queen's Cancer Research Institute at Queen's University in Kingston, Ontario, found no increased risk among women who worked that shift fewer than 30 years.