Women who have been treated for breast cancer are at risk for a recurrence of cancerous tumors in the years following treatment. Women treated with surgery, radiation, or chemotherapy for certain types of breast cancer may be prescribed tamoxifen, a drug that reduces the risk of recurrence. A recent study indicates women taking tamoxifen who also drink a small to moderate amount of coffee every day cut their risk of cancer recurrence by approximately half.

Tamoxifen is an antiestrogen, a chemical agent that blocks the activity of the hormone estrogen. Some forms of cancer, the estrogen receptor-positive (ER+) form, requires an interaction between estrogen and cancer cells in order to create tumors. Tamoxifen latches onto estrogen, preventing it from latching onto a cancer cell, thereby minimizing the likelihood of tumor development.

In a 2013 study from Lund University, Sweden, researchers discovered that women who drank coffee every day while taking tamoxifen were less likely to experience breast cancer recurrence than women taking tamoxifen who did not drink coffee. That study was designed to identify an association only, not the reason why coffee drinkers developed fewer tumors after breast cancer treatment.

The research team, led by Dr. Ann H. Rosendahl, has recently published the findings of a follow-up study that explored what, exactly, coffee does to help minimize breast cancer recurrence. They found two compounds in coffee responsible for reduced tumor development in ER+ patients as well as in estrogen-negative (ER-) patients.

From a data pool of 1,090 female breast cancer patients, 24 to 99 years old who had all been treated for breast cancer between 2002 and 2012 at Lund’s Skåne University Hospital, the researchers identified approximately 500 who were taking tamoxifen. All women in the study received the same preoperative exam and lifestyle questionnaire, which asked about the use of hormones and other medications and lifestyle factors which included the consumption of tobacco products, alcohol, and coffee. All patients were followed for at least 10 years after surgery for cancer recurrence.

The coffee drinkers were categorized by how much they drank on a regular basis:

  • Low consumption — less than one cup a day.
  • Moderate — 2 to 4 cups a day.
  • High — 5 or more cups a day.

The research revealed the rate of recurrence was lowest in women who took tamoxifen and drank two or more cups of coffee a day. The tumors these women did develop were smaller in size and fewer of them were estrogen-dependent tumors.

Two coffee compounds were found to be especially beneficial in the fight against recurring cancer: caffeine and caffeic acid. These compounds prevented the rapid cell division characteristic of cancer while increasing the cellular death rate in the cancer cells that did develop. In laboratory tests, these compounds alone proved measurable protection against tumor development but their cancer-killing effect became even stronger when tamoxifen was added.


  1. Rosendahl, Ann H, et al. "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 2015.21 (2015): 1877+. Web. 26 May 2015.
  2. "Tamoxifen." MedlinePlus. US Department of Health and Human Services, 19 May 2015. US National Library of Medicine. Web. 26 May 2015.
  3. "Can Coffee Be Good For You?" Day In Day Out. Wellness Council of America, n.d. WELCOA Online Bulletin. Web. 26 May 2015.


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