Analysis of 400 studies found risk of secondary cancer ranges from 6% to 22% depending on different factors
Women diagnosed with breast cancer under the age of 35 face a higher risk of it spreading, according to the first global study of its kind.
Breast cancer is the most common form of cancer, with 2.3 million people diagnosed every year. Survival rates are generally good, which is largely because of screening, early diagnosis and improved treatment.
