The fluids that often accumulate in the arm following breast cancer surgery, radiation or chemotherapy are not all the same. A tape measure, the common means of tracking fluid build-up, offers no discernment between intracellular and extracellular fluids, fat or lymphatic fluid build-up.
Bioimpedance spectroscopy (BIS), however, has that power of discernment. An ongoing multinational trial, PREVENT, which compares morbidity outcomes and time to lymphedema treatment intervention between the two methods is demonstrating multiple benefits with BIS use. Principal investigator Sheila H. Ridner, Ph.D., director of graduate studies and the Ph.D. in Nursing Science program at Vanderbilt University School of Nursing, launched the study in 2014.
Ridner sees three primary benefits patients can derive through BIS: earlier sleeve and gauntlet intervention for preclinical levels of lymphatic fluid build-up, fewer false positives, (impacting patients’ mental health), and deferred or obviated physical therapy.
“This is a relatively low-cost, simple way to more accurately measure lymphatic fluid build-up, as opposed to the standard tape measure method. We hope physicians will see that this technology should be used at every visit, before and after someone has had breast surgery,” Ridner says.
The BIS Difference
BIS determines the composition of body tissues by measuring the resistance frequency of current applied between two electrodes. When used for fluid measurement, the type of fluid makes a significant difference in whether and how the build-up will proceed. Intracellular fluids and most intercellular fluid that may accumulate after surgery will attenuate, but if it is lymphatic fluid, it needs to be recognized early on.
BIS can discern and measure lymphatic fluid with high accuracy. “When we see a patient with a reading of 6.5 L-DEX units (or a 5% increase in arm volume), which is the threshold for preclinical lymphedema, it is time to intervene with compression garments,” Ridner says. This can prevent not only chronic disfigurement and disability of the arm and infection risk, but also psychological trauma.
“In a woman who has just fought cancer and may have also lost one or both of her breasts, having a new and possibly permanent arm disability is devastating. In fact it is the number one fear of breast cancer survivors,” she said.
“In a woman who has just fought cancer and may have also lost one or both of her breasts, having a new and possibly permanent arm disability is devastating. In fact it is the number one fear of breast cancer survivors.”
The PREVENT Study
To date, 1,201 patients have been enrolled pre-surgery and randomized to either the tape measure or BIS group. 508 have completed baseline measurements and had follow-up measurements 90 days after surgery, and regularly thereafter, for at least 12 months post-surgery. Ridner anticipates that the trial will close at the end of 2020, and will include outcomes for patients with up to three years of post-surgery follow-up.
Sixty-eight (28.5%) patients in the tape measurement group and 41 (15.8%) in the BIS group have developed preclinical lymphedema. These patients wore the compression garments 12 hours a day for 28 days. Significantly, the mean time to reach that threshold was 2.8 months and 9.5 months, respectively.
Also notably, the BIS patients were much less likely to require complex decongestive physiotherapy (CDP) than the tape measure group. 14.7 percent of the patients in the tape measure group developed clinical lymphedema that required CDP. Only 4.9 percent required this treatment in the BIS group.
“The study tells us that more accurate readings lead to more time-appropriate use of the compression sleeves, thus reducing the risk of reaching preclinical lymphedema. It also tells us that the majority of patients who do reach the threshold reach it much later,” Ridner says.
According to Ridner, avoiding lymphedema that requires CDP can save about $25,000 per patient over the two years after breast cancer treatment. Treatment of infections like cellulitis, counseling for mental health problems and antidepressant medications all contribute to the cost when fluid build-up is mischaracterized or underestimated.
The next generation BIS device, the SOZO, works without electrodes and is currently in use at a number of clinics and institutions globally. Home use may not be far behind. Ridner says, “As one of my patients told me, ‘if we have home glucose monitors to measure blood sugar, why on earth don’t we have a device for measuring fluid build-up?'”