A number of studies have shown that coffee helps to protect against breast cancer and new work led by Lund University has found that it also inhibits the growth of tumors and reduces risk of recurrence in women who have been treated with the drug tamoxifen.

In the cell study, the researchers looked more closely at two substances that usually occur in the coffee drunk in Sweden – caffeine and caffeic acid - and is a follow-up of the results the researchers obtained two years ago. 

“Now, unlike in the previous study, we have combined information about the patients’ lifestyle and clinical data from 1,090 breast cancer patients with studies on breast cancer cells. The study shows that among the over 500 women treated with tamoxifen, those who had drunk at least two cups of coffee a day had only half the risk of recurrence of those who drank less coffee or none at all,” explain Lund researchers Ann Rosendahl and Helena Jernström, who obtained the results in collaboration with Jeff Holly and his research team at University of Bristol. “The study also shows that those who drank at least two cups of coffee a day had smaller tumours and a lower proportion of hormone-dependent tumors. We saw that this was already the case at the time of diagnosis.

“The breast cancer cells reacted to these substances, especially caffeine, with reduced cell division and increased cell death, especially in combination with tamoxifen. This shows that these substances have an effect on the breast cancer cells and turn off signaling pathways that the cancer cells require to grow.”

The researchers have demonstrated both in breast cancer patients and at cell level that coffee appears to reinforce the effect of treatment with tamoxifen.

"Just two cups a day is sufficient to make a difference.”

Citation: Ann H. Rosendahl, Claire M. Perks, Li Zeng, Andrea Markkula, Maria Simonsson, Carsten Rose, Christian Ingvar, Jeff M.P. Holly, Helena Jernström, 'Caffeine and Caffeic Acid Inhibit Growth and Modify Estrogen Receptor and Insulin-like Growth Factor I Receptor Levels in Human Breast Cancer', Clinical Cancer Research