Lee J1, Mastick J2, Smoot B1,3, Miaskowski C2
1University of California/San Francisco State University, Graduate Program in Physical Therapy, San Francisco, United States, 2University of California, Physiological Nursing, San Francisco, United States, 3University of California, Physical Therapy and Rehabilitation Sciences, San Francisco, United States
Background: Increased arm volume in lymphedema (LE) is due to an accumulation of interstitial fluid. However, increases in limb volume in chronic LE may also be related to changes to adipose and muscle tissue. Changes in tissue composition may explain why treatments fail in patients with chronic LE. It is not clear to what extent the increase in limb volume is due to fluid, fat, and/or muscle. Dual-energy x-ray absorptiometry (DXA) can be used to estimate excess fat and/or muscle in patients with LE.
Purpose: The purposes of this study are to compare the soft tissue composition of the affected and unaffected arms of women with and without LE post breast cancer (BC), and to compare differences between groups.
Methods: Data were analyzed for 248 women enrolled in an ongoing cross-sectional study. Women were required to be >6 months post active treatment for unilateral BC. Women were dichotomized into those with (n=96) and without arm LE (n=152), based on previous diagnosis by a healthcare provider. Informed consent was obtained. Demographic and clinical information were collected by questionnaire. DXA was performed using the Horizon DXA/A System (Hologic Inc, Apex 5.6.0.4). Data on arm fat, lean mass, and % fat are reported. Descriptive statistics were calculated for demographics and relevant outcomes. T-tests and ANOVA were used to evaluate within and between-group differences and interaction effects.
Results: Mean age: 61.7 years (10.4); BMI: 26.8 kg/m2 (5.4), with no differences between women with and without LE. There were no differences between groups for side of cancer, dominant arm, or if the treated side was the dominant side. The dominant arm was the right side in 220 women (89%). The dominant side was the treated side in 131 women (53%). Fat mass, fat free mass, and % fat were consistently higher in the women with LE in both the affected and unaffected arms compared to the women without LE. These differences were statistically significant (p 0.05) between groups (LE vs no LE) for all but fat free mass and % fat in the unaffected arm. Fat mass and fat free mass were higher in the affected than unaffected arms in the women with LE (p 0.05); % fat was higher, though not statistically significant (p=0.019). Fat mass, fat free mass, and % fat were lower in the affected than the unaffected side in the women without LE, though only statistically significant for fat mass. The interaction effects (comparing inter-arm differences between groups) were statistically significant for all outcomes (p 0.05).
Conclusion(s): Women with LE demonstrated greater fat mass and fat free mass in their affected arm than their unaffected arm. This was not the case for the women without LE.
Implications: DXA is able to estimate the volumes of specific tissues in the arm. It is possible, that based on changes in soft tissue composition of the lymphedematous arm, we may be better able to stage LE and to provide targeted LE interventions for improved outcomes.
Keywords: breast cancer, lymphedema, DXA
Funding acknowledgements: n/a
Purpose: The purposes of this study are to compare the soft tissue composition of the affected and unaffected arms of women with and without LE post breast cancer (BC), and to compare differences between groups.
Methods: Data were analyzed for 248 women enrolled in an ongoing cross-sectional study. Women were required to be >6 months post active treatment for unilateral BC. Women were dichotomized into those with (n=96) and without arm LE (n=152), based on previous diagnosis by a healthcare provider. Informed consent was obtained. Demographic and clinical information were collected by questionnaire. DXA was performed using the Horizon DXA/A System (Hologic Inc, Apex 5.6.0.4). Data on arm fat, lean mass, and % fat are reported. Descriptive statistics were calculated for demographics and relevant outcomes. T-tests and ANOVA were used to evaluate within and between-group differences and interaction effects.
Results: Mean age: 61.7 years (10.4); BMI: 26.8 kg/m2 (5.4), with no differences between women with and without LE. There were no differences between groups for side of cancer, dominant arm, or if the treated side was the dominant side. The dominant arm was the right side in 220 women (89%). The dominant side was the treated side in 131 women (53%). Fat mass, fat free mass, and % fat were consistently higher in the women with LE in both the affected and unaffected arms compared to the women without LE. These differences were statistically significant (p 0.05) between groups (LE vs no LE) for all but fat free mass and % fat in the unaffected arm. Fat mass and fat free mass were higher in the affected than unaffected arms in the women with LE (p 0.05); % fat was higher, though not statistically significant (p=0.019). Fat mass, fat free mass, and % fat were lower in the affected than the unaffected side in the women without LE, though only statistically significant for fat mass. The interaction effects (comparing inter-arm differences between groups) were statistically significant for all outcomes (p 0.05).
Conclusion(s): Women with LE demonstrated greater fat mass and fat free mass in their affected arm than their unaffected arm. This was not the case for the women without LE.
Implications: DXA is able to estimate the volumes of specific tissues in the arm. It is possible, that based on changes in soft tissue composition of the lymphedematous arm, we may be better able to stage LE and to provide targeted LE interventions for improved outcomes.
Keywords: breast cancer, lymphedema, DXA
Funding acknowledgements: n/a
Topic: Oncology, HIV & palliative care; Outcome measurement
Ethics approval required: Yes
Institution: University of California San Francisco
Ethics committee: Human Research Protection Program Institutional Review Board
Ethics number: 14-15263
All authors, affiliations and abstracts have been published as submitted.
