ASBrS 2019: Bioimpedance Spectroscopy for Surveillance of Breast Cancer–Related Lymphedema
Surveillance of women at risk for breast cancer–related lymphedema using bioimpedance spectroscopy was more effective in preventing lymphedema progression than traditional arm circumference measurement when each was combined with immediate compression therapy. These were the results of an interim analysis of 508 patients in a large, multisite, international, randomized controlled trial comparing the detection of early lymphatic impairment using technology that directly measures extracellular fluid with conventional tape measure assessment. These findings were presented by Dietrich et al at the Annual Meeting of the American Society of Breast Surgeons (ASBrS).
“Breast cancer–related lymphedema is a chronic, debilitating swelling of the arm that may result from surgery, radiation, or chemotherapy affecting the lymph nodes. Lymphedema significantly lowers quality of life and consistently ranks as the number one fear of breast cancer survivors,” said lead study author Sheila Ridner, PhD, RN, FAAN, of Vanderbilt University School of Nursing. Dr. Ridner added that this is the first trial of this type to demonstrate the efficacy of bioimpedance spectroscopy over tape measure assessment to prevent progression of lymphedema through early lymphatic impairment detection, followed by immediate intervention with compression therapy using specially fitted sleeves and gauntlets.
“This study suggests that [bioimpedance spectroscopy] is a highly effective tool for pinpointing patients at risk,” said Dr. Ridner. She also reported that fewer women went on to develop clinical lymphedema when referred for therapy using [bioimpedance spectroscopy] than tape measure assessment.
Study Methods
The prospective study enrolled patients prior to cancer treatment who were undergoing mastectomy and/or a range of lymph node–related breast cancer surgeries and/or radiation. After baseline measurements, patients were randomly assigned to either the bioimpedance spectroscopy or tape measure groups. Starting at 90 days postsurgery, patients were regularly assessed and followed for a minimum of 12 months after surgery for this interim analysis.
Patients in the tape measure group who experienced an increase in arm circumference of 5% or more (reflective of subclinical lymphedema) were treated with compression therapy. For patients evaluated with bioimpedance spectroscopy, an increase of 6.5 L-DEX units from baseline (also reflective of a subclinical lymphedema) triggered therapeutic intervention. Therapy consisted of arm compression using a precisely fitted sleeve and chest gauntlet for 12 hours daily for 28 days.
Results
In the study, 68 patients (28.5%) in the tape measure group and 41 (15.81%) in the bioimpedance spectroscopy group—or 21% of the overall participants—met the thresholds and underwent therapeutic intervention. The mean time to reach thresholds was 9.5 months for bioimpedance spectroscopy and 2.8 months for tape measure.
Ten tape measure patients (14.7%) whose assessments triggered clinical interventions later developed clinical lymphedema requiring complex decongestive therapy vs two in the bioimpedance spectroscopy group (4.9%). This represents a 67% relative reduction and a 9.8% absolute reduction (P = .130) using bioimpedance spectroscopy measurement. For both groups, clinical lymphedema was defined as a 10% increase in arm circumference with tape measure assessment.
Study Implications
Dr. Ridner noted that results were extremely encouraging. “These findings mean that women could potentially avoid this debilitating condition if [bioimpedance spectroscopy] screening were the norm,” she said.
Perhaps surprisingly, although more tape measure patients received early intervention, more also went on to suffer clinical lymphedema. Dr. Ridner explained that significant fluid accumulation is required for measurable increases in arm circumference. Additionally, tape measure assessment also includes fat, bone, soft tissue, and other fluids that may result from the trauma of cancer treatment, complicating interpretation. Moreover, tape measure assessment leaves more room for human error. By contrast, bioimpedance spectroscopy relies on electrical current to gauge fluid resistance between cells, providing extremely specific and precise measurements.
Dr. Ridner explained that bioimpedance spectroscopy is a relatively low-cost, fast, and noninvasive assessment tool. It not only potentially enhances patient care, but also may save the significant expense of decongestive physical therapy if later required.
The clinical trial was launched in June 2014 and will follow all 1,201 enrolled patients for 3 years postsurgery. Currently, enrollment is complete, and 200 patients have completed the full protocol.
Disclosure: For full disclosures of the study authors, visit breastsurgeons.org.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
