Several scientific studies have shown that coffee has a protective effect against breast cancer and other cancers. A new Swedish research study now sheds light on why coffee can, at least when it comes to the silent killer cancer, be considered a health drink.
"The caffeine turns off the signal paths to breast cancer cells. This results in slower cell proliferation and increased cell death," said Ann Rosendahl, a researcher at Lund University and co-author of the recent report detailing how coffee protects against breast cancer recurrence.
The report has just been published in the medical journal Clinical Cancer Research.
Researchers in Lund demonstrated two years ago, together with a British research team, that a couple of cups of coffee a day helped to prevent recurrence of breast cancer, especially in patients concomitantly treated with the (anti-hormone) drug Tamoxifen.
"We have now gone down into the cellular level and thus gained a greater understanding of the underlying causes," said Rosendahl.
The researchers have focused their studies on caffeine and caffeine acid, common substances in coffee, and how caffeine in particular affects the signalling pathways that cancer cells need to grow. The study involved almost 1100 women, of whom more than 500 were also taking the drug tamoxifen.
"For the women treated with tamoxifen and who drank at least two cups of coffee a day, the risk of relapse is almost half that of those who drank a small quantity of coffee or no coffee at all," Rosendahl explained.
The prior Swedish-British study involved only women who have already been diagnosed and treated for breast cancer. But the researchers were also able to observe that coffee has a preventive effect.
"Already at diagnosis it was found that the cancer was less well developed in coffee drinkers than among the rest," said Ann Rosendahl, who drinks three cups of coffee a day herself.
Several studies support the contention that coffee reduces the risk of various cancers and may protect against relapse.
Those who drink at least four cups of coffee daily have a 20 percent lower risk of skin cancer (malignant melanoma) than those drinking the least (National Cancer Institute, 2015).
For men who drink more than six cups of coffee a day the risk of developing a fatal cancer drops by 60 percent. Three cups per day cuts the odds by 30 percent, according to a 2011 study published in the Journal of the National Cancer Institute.
Furthermore five cups of coffee a day reduces the risk of the more aggressive form of breast cancer, according to a research study published by the Karolinska Institute in 2011.