Assessment of segmental arm soft tissue composition in breast cancer-related lymphedema: a pilot study using dual energy X-ray absorptiometry and bioimpedance spectroscopy.

BACKGROUND: Changes in arm soft tissue composition, especially increased adipose tissue, has been found in advanced, non-pitting breast cancer-related lymphedema (BCRL). The aim of this study was to examine whether these changes were localized to any particular region of the arm and whether they occurred in lymphedema which still pitted to pressure. Secondary aims were to explore relationships between arm segment volumes, bioimpedance spectroscopy (BIS) measurements of extracellular fluid (ECF), and dual-energy X-ray absorptiometry (DXA) measurements of tissue composition. METHODS AND RESULTS: Nine women with unilateral BCRL participated. The dominant arm was affected in 4 women, and all presented with lymphedema that pitted to pressure. Arm volume was calculated from circumferences by the truncated cone method, ECF was determined with BIS and fat and lean tissue content measured by DXA. BIS and DXA measurements for women with lymphedema were made of the whole arm and also of four 10 cm-segments measured from the ulnar styloid at the wrist. Whole arm DXA data were compared to those of 45 women of similar age and body mass index without lymphedema. All women with lymphedema had a significantly larger absolute fat mass in their affected arm compared to their unaffected arm, (median difference between arms 146.9 g). The forearm segment 10 - 20 cm proximal to the wrist had the highest median inter-limb fat difference of all four arm segments. CONCLUSIONS: The soft tissue composition changes associated with BCRL may occur in the presence of pitting and predominantly affect the proximal forearm.

Assessment of breast cancer-related lymphedema: a comparison of moisture meter and spot bioimpedance measurement.

BACKGROUND: Tissue dielectric constant (TDC) and spot bioimpedance measurement (BIA) have a role in the assessment of tissue composition changes in breast cancer-related lymphedema (BCRL). Our aims were to determine whether TDC and spot BIA measures could detect inter-limb differences in BCRL, explore the relationship between methods, and establish the intra-rater reliability and technical error of measurement for TDC. METHODS AND RESULTS: Women with (n=20) and without (n=4) unilateral BCRL participated. Circumference, TDC, and spot BIA measures were completed on the most affected region of the arm for BCRL participants and at a standardized forearm point in women without lymphedema. All measures were compared to measurements from an identical location on the contralateral arm. The affected arm differed significantly to the unaffected arm of women with BCRL for TDC and spot BIA measures. The median (IQR) differences were: extra-small probe 5.75 (3.10-8.21), small probe 3.50 (1.16-6.89), medium probe 5.08 (0.88-10.91), and for spot BIA measurement (-35.20 Ω; -59.75 to -14.85 Ω). The small and medium TDC probe measures were moderately correlated to spot bioimpedance measurements (r=-0.54 and r=-0.43, respectively). Intra-rater reliability coefficients (ICC2,1) of TDC measures ranged from 0.50 (95% CI: 0.12-0.75) to 0.92 (0.82-0.96). TDC technical error of measurement for women with lymphedema varied from 10.5% to 13.3%. CONCLUSIONS: Both TDC and spot bioimpedance may have a role in clinical assessment of tissue compositional change in BCRL. Their relationship with tissue composition, assessed by imaging, is now required.