"In this large cohort of women, with 22 years of follow-up, we observed no association between coffee (caffeinated or decaffeinated) and tea consumption and the risk of breast cancer," Dr. Davaasambuu Ganmaa said.

"Coffee and tea are remarkably safe beverages when used in moderation," said Ganmaa, of the Harvard School of Public Health in Boston, Massachusetts.

Ganmaa and colleagues assessed coffee, tea, and caffeine consumption among 85,987 women who participated in the Nurses' Health Study and who were between 30 and 55 years old at the start of the study.

Over 22 years of follow up, 5,272 women developed breast cancer.

The researchers found no elevated risk of breast cancer among women who reported drinking four or more cups of caffeinated or decaffeinated coffee or tea per day, compared with those who drank less than one cup daily.

The external factors taken into account included: age, family history, body mass, smoking status, physical activity, alcohol intake, number of children, history of hormone therapy, and menopausal status.

The research also showed no association between intake of other caffeinated beverages and chocolate and breast cancer.