Year: 2009
Type: article
Study design: Observational Study
Abstract: Etiologic factors such as vitamin D and estrogen are potentially related to breast cancer development, although details of their mechanisms are not completely understood. We prospectively investigated correlates of breast cancer risk among postmenopausal women in the Study of Osteoporotic Fractures (SOF). First, we undertook a case-cohort study to test the hypothesis that low serum 25-hydroxyvitamin D [25(OH)D] will be associated with an increased risk of ER+ breast cancer (N=502). Low 25(OH)D levels were not associated with an increased risk of breast cancer and do not support an association between 25(OH)D and ER+ breast cancer development. Second, we utilized fractional calcium absorption (FCA) as a marker of tissue resistance to vitamin D to test the hypothesis that low FCA will be associated with an increased risk of breast cancer (N=5035). To the contrary, over a mean 9.6 years, increasing rates of FCA were associated with a higher risk of invasive breast cancer. A stronger positive relationship was noted among women with low dietary calcium intake. The findings support a modestly increased risk of breast cancer with higher FCA rates particularly among those who have low calcium intake. Finally, we examined the long-term association of an initial bone mineral density (BMD) measure and change in BMD (annual percent change assessed 3.5 years later) on breast cancer risk (N=5385). Furthermore, we tested the hypothesis that the risk associated with an initial BMD measure would be strengthened by the addition of the change variable. Over a mean 9.5 years, there was no association between increasing levels of BMD, change in BMD, or a combined model and breast cancer. The effect of BMD was found to be dependent upon family history of breast cancer. Among women with a positive family history, high BMD was associated with a 3-fold higher risk of breast cancer compared to low BMD. Through our investigations of two etiologic factors and their association with breast cancer development, we have enhanced our knowledge regarding the interdependence of vitamin D, calcium, and estrogen. These findings may lead to improved opportunities for prevention and early detection and are of significant public health relevance.
Author: Jessica Albano
Language: English
Topic: Vitamin D Research Studies
Subfield: Endocrinology, Diabetes and Metabolism
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W983121349