Caffeine and Breast Cancer: Enjoy that Cup of Java

Caffeine is almost certainly the country’s most popular drug, with American adults consuming more than 300 milligrams of it every day. Caffeine is a natural component of chocolate, coffee and tea and is used in most colas and energy drinks. It is also found in diet pills and some over-the-counter pain relievers and medicines. Over the past 30 years, there have been more than 19,000 studies on caffeine and coffee in an attempt to determine its exact effects on the human body. While caffeine is known to have some negative effects such as increasing anxiety, stress, food cravings and inhibiting sleep, increasing the overall risk of breast cancer isn’t one of them, according to a recent study.
Earlier research focusing on women diagnosed with non-cancerous breast cancer revealed that, for these patients, cutting caffeine from their diet could improve symptoms. Since benign breast disease is considered a risk factor for developing the malignant form, the findings raised concerns that caffeine might also increase the risk for malignant breast cancer.
With this in mind, Dr. Shumin M. Zhang from the division of preventive medicine at Brigham and Women’s Hospital and Harvard Medical School in Boston, along with colleagues from Tokyo Women’s Medical University in Japan studied the diets of 38,432 women over the period of four years, between 1992 and 1995. All of the women were over the age of 45 and worked as health-care professionals, the majority being registered nurses. The researchers found that about 25 percent never drank coffee, and about another 25 percent drank either one cup or less per day. Almost 30 percent consumed two to three cups per day, while slightly more than 15 percent drank four or more cups daily.
Within 10 years of follow-up, 1,188 of the study participants developed invasive breast cancer. However, after taking the women’s dietary information into account, the researchers concluded that consuming caffeine in any of its forms was not significantly associated with overall breast cancer risk. However, those with a history of benign breast disease who consumed caffeine at the highest end of the scale did have a “borderline significantly increased risk” for developing the malignant form of the disease.
The team also found that high amounts of caffeine raised the risk for certain subgroups. Those at risk for developing certain forms of breast cancer known as estrogen and/or progesterone receptor-negative breast cancer rose by 68 percent with heavy caffeine consumption and the risk for developing tumors larger than two centimeters rose by 79 percent. Since these types of breast cancer and larger tumors are associated with poorer outcomes, the team notes that it’s important to continue to investigate the impact of caffeine on specific kinds of breast cancer, even if the general risk remains insignificant.
A study last year by nutrition researcher Walter Willett, MD and colleagues from the Harvard School of Public Health also found no association between coffee or caffeine consumption and an increase in breast cancer risk or between caffeine and ER/PR negative or large tumors. The study did suggest a slight increase in breast cancer risk among postmenopausal women. But Dr. Willett says women should not be overly worried by the subgroup finding. “I wouldn’t pay too much attention to this,” he tells WebMD. “The consistent thing in all the research is that nobody has seen an overall increase in breast cancer risk.”
Dr. Willett noted that after decades of researching caffeine, coffee and health, there is very little to suggest an impact, either positive or negative, on any cancer. “In fact, it is very hard to pin anything on coffee or caffeine at this time,” WebMD quoted him as saying. “It is fair to say that, so far, the overall balance of risks and benefits are on the side of benefits.”
Recent studies have shown that coffee and caffeine may have some significant medical benefits. A study by Harvard University examined 126,000 people over an 18-year period. Their findings indicated that people who drink one to three cups of coffee per day are up to 9 percent less likely to contract diabetes. Men who drank six or more cups of coffee a day slashed their chances by 54 percent and women by 30 percent. Other studies have shown similar results in the development of Parkinson’s disease, colon cancer, cirrhosis and gallstones. It has also been shown to be beneficial in asthma, stopping headaches, boosting mood and even preventing cavities.
But despite the recent findings, most doctors still recommend moderation in regard to caffeine intake. Researchers say women who drink heavy amounts of caffeine tend to have other not-so-healthy lifestyle habits that may be linked to breast cancer risk.
The Zhang study, funded by the National Institutes of Health, was published in the October 13 issue of Archives of Internal Medicine.