Background: Quantitative measurements to help detect incipient or latent lymphedema in patients at risk for breast cancer treatment-related lymphedema (BCRL) are potentially useful supplements to clinical assessments. Suitable measurements for routine use include arm volumes, arm bioimpedance, and local tissue water (LTW) determined from the tissue dielectric constant (TDC). Because BCRL initially develops in skin and subcutis, measures that include whole arms may not be optimally sensitive for detecting the earliest changes. Thus, there is also a need for a local measurement in which tissues most likely to demonstrate early lymphedematous changes can be more selectively assessed. The TDC method satisfies this criterion. Our goal was to use this method to compare arm-to-arm differences in LTW within and among women grouped as healthy normal (HN), diagnosed with breast cancer (BC), but prior to surgery and established unilateral lymphedema (LE).
Methods and results: LTW was determined on both anterior forearms to a measurement depth of 2.5 mm in 30 women of each group. TDC arm ratios were determined as dominant/nondominant for HN and BC, at-risk/contralateral for BC, and lymphedematous/contralateral for LE. Results showed that TDC values for all arms except lymphedematous arms were very similar and insignificantly different with values among arms (mean +/- SD) ranging from 24.9 +/- 3.8 to 25.7 +/- 3.8. Arm ratios did not differ between HC and BC whereas dominant/non-dominant arm ratios for HN and BC separately and combined (1.006 +/- 0.085) were significantly less than the lymphedematous/contralateral ratio of the LE group (1.583 +/- 0.292).
Conclusions: The findings indicate that LTW of at-risk arms is not affected by breast cancer and that lymphedema does not significantly affect LTW of contralateral arms as measured with the TDC method. Further, based on the standard deviation of measured arm ratios, an at-risk/contralateral TDC ratio of 1.26 is suggested as a possible threshold for detecting preclinical or latent lymphedema.