The coffee (caffeine)/breast cancer relationship

This study by researchers at Malmö University in Sweden suggests that the development of breast cancer might be delayed in women who drink more than 2 cups of coffee each day and have a certain form of the enzyme CYP1A2.

Before you drink more coffee, read on.

First, the details.

  • The authors determined the type of CYP1A2 in 458 patients with breast cancer (age, 25-99 years).
    • Caffeine is metabolized by the cytochrome P4501A2 (CYP1A2) liver enzyme.
  • Information on lifestyle and tumor characteristics were obtained from questionnaires and pathology reports.

And, the results.

  • Coffee’s effect varied depending on the type of CYP1A2 gene present.
  • Half of the women had a variant of CYP1A2 called A/A — the rest had either A/C or C/C.
  • Women who were A/C or C/C and drank at least 3 cups of coffee a day developed breast cancer considerably less (2/3 less) often than women with the A/A variant and the same coffee consumption.
  • Cancer in A/A women who drank at least 2 cups of coffee appeared later compared to women who seldom or never drank coffee (diagnosis at 58 instead of 48 years old).
    • Women who develop breast cancer when they are older often do better than those who get it earlier in life.
  • A history of hormone replacement therapy for menopausal symptoms canceled this relationship.

The bottom line?
Dr. Helena Jernstrom is cautious about her findings. “This is new information that needs to be corroborated … before we can issue any recommendations. If coffee does in fact provide some protection against breast cancer, then women in such a coffee-drinking country as Sweden ought to have fewer cases of cancer than other countries.”

In support of her view, Dr. Jernstrom says that the incidence of breast cancer in Sweden is lower compared to the US where women drink more decaffeinated coffee and less coffee in general. Further support comes from a study in Finland where coffee appeared to be protective against breast cancer in postmenopausal women.

Others, however, have found no relationship (or a weak relationship) between coffee consumption and breast cancer risk.

In fact, it appears that caffeine rather than coffee is the key factor.

The results from a study published in 2007 suggested, “that caffeine protects against breast cancer in women that have a BRCA1 gene mutation.” BRCA1 stands for “breast cancer 1, early onset.” The BRCA1 gene suppresses tumors, and mutation of this gene increases the risk for breast cancer.

Dr. Jernstrom is correct when she says more research is necessary.

4/27/08 21:18 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.