Breast cancer 'link to night shifts'

A study has shown that women who worked 30 or more years of night shift work had double the risk of breast cancer compared with people who had never worked night shifts.

Dr Jane Green, clinical epidemiologist at Oxford University, explained to Today programme presenter John Humphrys that the length of time women worked night shifts was an important factor in the study's conclusions:

"It is very long term nightshift working which has been associated with breast cancer risk in most but not all studies."

"This study adds to what we already know. It's not the final word - it's another piece in the jigsaw," she added.

First broadcast on the Today programme on Tuesday 2 July.