The British Journal of Cancer reported on March 16, 2010, on a case-control study that included 6,000 Wisconsin women, half of whom had breast cancer. The study found that bisphosphonates reduced the risk of breast cancer by 30 percent. ”This large study provides new evidence that the use of bisphosphonates can reduce the potential risk of breast cancer.” Polly Newcomb, leader of the Cancer Prevention Program at the Frederik Cancer Research Center, said in a statement. The study is similar in its results for reducing the risk of developing breast cancer to two other studies already reported at the San Antonio Breast Cancer Summit in December 2009. One study from the U.S. Women’s Health Organization included 150,000 postmenopausal women and found that bisphosphonates reduced the risk of breast cancer by 32 percent, and another study from Israel included 4,575 postmenopausal women and found that bisphosphonates reduced the risk of breast cancer by 34 percent. Theresa Guise, MD, of Indiana State University Medical Center, found the news of identical findings in two geographically diverse populations to be encouraging, but cautioned that the results need to be confirmed by a randomized controlled clinical trial. Some possible confounding factors need to be analyzed, such as low bone density in women treated with bisphosphonates for osteoporosis itself, which may be caused by low estrogen levels, a risk factor for breast cancer. In their final study, Dr. Newcomb and his colleagues emphasized that body mass index and postmenopausal hormone use are also important to consider. In addition, bisphosphonates tend to be used in patients with fractures, height loss, and physician-diagnosed osteoporosis, suggesting that the use of bisphosphonates associated with reduced breast cancer risk is only in women with signs and symptoms of bone loss. However, the results of the study found no significant association between this bone loss and the ability of bisphosphonates to reduce the potential risk of breast cancer. ”The association that bisphosphonates reduce the potential risk of breast cancer is not attributable to primary indications for use such as bone density loss and fractures.” The authors show. The researchers conclude that the reduction in the potential risk of breast cancer by bisphosphonates may be due to the anti-tumor mechanism of bisphosphonates. However, this association of bisphosphonate use with reduced breast cancer risk was only in non-obese populations, suggesting that the inhibitory effect of the drug is related to hormonal threshold effects or other growth factors, including some of the important breast cancer development factors that have been elucidated, high estrogen levels in obese women, and the ability of bisphosphonates to reduce breast cancer risk only at certain hormone levels The ability of bisphosphonates to reduce the risk of breast cancer can only be achieved at certain hormone levels. The mechanism of how bisphosphonates reduce the risk of breast cancer is unknown and may be related to several effects of the drug, which can cause apoptosis, inhibit angiogenesis and prevent adhesion of tumor cells. “This drug can affect important functions associated with cell growth and death, particularly tumor cell death, and even some precancerous lesions.” Dr. Newcomb writes in the article. Large studies have already reported beneficial antitumor effects of bisphosphonates when applied in patients who already have breast cancer. The recent Journal of Clinical Oncology (2009;27:4043-4046) discusses the seed and soil hypothesis of cancer development, with diphosphonates contributing to the unfavorable soil that stops cancer cells from developing.