Within approximately a decade following the collection of dietary information, almost 1,190 of the women developed invasive breast cancer.
Yet, consuming caffeine in any of its forms was not found to be significantly associated with breast cancer risk.
However, among those with a history of benign breast cancer disease, those consuming caffeine at the highest end of the scale did have a "borderline significantly increased risk" for malignant disease. A similar positive link was found between caffeine consumption and the risk for developing tumors larger than two centimeters. Caffeine raised the risk for such tumors by 79 percent, Zhang and his team found.
As well, the risk for developing certain forms of breast cancer -- known as estrogen and/or progesterone receptor-negative breast cancer -- also rose with caffeine consumption by 68 percent, the researchers noted.
The team pointed out that since such types of breast cancer and/or tumors in excess of two centimeters are associated with poorer outcomes, it's important to continue to investigate whether or not caffeine truly has a negative impact on the ongoing development of specific kinds of breast cancer -- even if the general risk remains insignificant.
Dr. Alan Astrow, director of the division of hematology/oncology at Maimonides Medical Center in New York City, suggested that the findings are both comforting and preliminary.
"Overall, the results of this study should be reassuring to women who are concerned about their risk of breast cancer and who also like to drink coffee moderately," he said. "However, the field of diet and breast cancer risk remains one of active research, and the results of these kinds of investigations are not always easy to interpret. It is possible that future st
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