Using the x-rays, the researchers calculated the thickness of a bone in each woman's hand to determine its density. These women were then monitored over a 26-year period, during which time 91 women developed postmenopausal breast cancer. After adjusting for multiple breast cancer risk factors, researchers determined that women in the highest bone mass group had 3.5 times the risk of getting breast cancer compared to those in the lowest quartile of bone mass. A variety of factors contribute to both maximizing bone mass and influencing breast development and the risk of breast cancer, according to Dr. Joan McGowan, director of the Musculoskeletal Diseases Branch of the National Institute of Arthritis and Musculoskeletal and Skin Diseases. However, he also cautioned that the findings should be kept in perspective since, for most women, estrogen may provide crucial benefits against heart disease and osteoporosis.
Heart disease is the leading cause of death among American women.
While about 44,000 women died of breast cancer in 1994, approximately 370,000 died of heart disease. The PEPI study also found that HRT increases bone density, helping to reduce the risk of osteoporosis, a severe thinning of the bones that can lead to an increased risk of bone fractures and serious complications including pain, loss of mobility, and death. About 25 million people in the U.S. have or are at risk of developing osteoporosis. Additional research is needed to pinpoint the modifiable risks associated with cancer, heart disease, and osteoporosis, and how they interrelate. For postmenopausal women who need to make treatment decisions now, before ongoing study results are available, Dr. Lenfant advised women to consult their physicians and weigh their individual health risks before deciding on the best course of action.