Disentangling the body weight-bone mineral density association among breast cancer survivors: an examination of the independent roles of lean mass and fat mass
1 Applied Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, Bethesda, MD 20892, USA
2 Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle WA, USA
3 Moores UCSD Cancer Center, Cancer Prevention and Control Program, University of California, San Diego CA, USA
4 Office of Cancer Survivorship, Division of Cancer Control and Population Sciences, National Cancer Institute, Bethesda MD, USA
5 Division of Chronic Disease Epidemiology, MD Yale School of Public Health, New Haven CT, USA
6 Department of Epidemiology and Population Health, University of Louisville, Louisville KY, USA
7 Department of Population Sciences, Beckman Research Institute, City of Hope, Duarte CA, USA
BMC Cancer 2013, 13:497 doi:10.1186/1471-2407-13-497Published: 25 October 2013
Bone mineral density (BMD) and lean mass (LM) may both decrease in breast cancer survivors, thereby increasing risk of falls and fractures. Research is needed to determine whether lean mass (LM) and fat mass (FM) independently relate to BMD in this patient group.
The Health, Eating, Activity, and Lifestyle Study participants included 599 women, ages 29–87 years, diagnosed from 1995–1999 with stage 0-IIIA breast cancer, who underwent dual-energy X-ray absorptiometry scans approximately 6-months postdiagnosis. We calculated adjusted geometric means of total body BMD within quartiles (Q) of LM and FM. We also stratified LM-BMD associations by a fat mass index threshold that tracks with obesity (lower body fat: ≤12.9 kg/m2; higher body fat: >12.9 kg/m2) and stratified FM-BMD associations by appendicular lean mass index level corresponding with sarcopenia (non-sarcopenic: ≥ 5.45 kg/m2 and sarcopenic: < 5.45 kg/m2).
Higher LM (Q4 vs. Q1) was associated with higher total body BMD overall (1.12 g/cm2 vs. 1.07 g/cm2, p-trend < 0.0001), and among survivors with lower body fat (1.13 g/cm2 vs. 1.07 g/cm2, p-trend < 0.0001) and higher body fat (1.15 g/cm2 vs. 1.08 g/cm2, p-trend = 0.004). Higher FM (Q4 vs. Q1) was associated with higher total body BMD overall (1.12 g/cm2 vs. 1.07 g/cm2, p-trend < 0.0001) and among non-sarcopenic survivors (1.15 g/cm2 vs. 1.08 g/cm2, p < 0.0001), but the association was not significant among sarcopenic survivors (1.09 g/cm2 vs. 1.04 g/cm2, p-trend = 0.18).
Among breast cancer survivors, higher LM and FM were independently related to higher total body BMD. Future exercise interventions to prevent bone loss among survivors should consider the potential relevance of increasing and preserving LM.