Purpose: Approximately 20 % of patients develop lymphedema (LE) following breast cancer (BC) surgery. An evaluation of distinct trajectories of volume change may improve our ability to diagnose LE sooner. The purposes of this study were to identify subgroups of women with distinct trajectories of limb volume changes following BC surgery and to evaluate for phenotypic differences among these classes.
Methods: In this prospective longitudinal study, 380 women were enrolled prior to unilateral BC surgery. Upper limb bioimpedance was measured preoperatively and serially for 1 year postoperatively. Resistance ratios (RRs) were calculated. A RR of >1 indicates affected limb volume > unaffected limb volume. Latent class growth analysis (LCGA) was used to identify classes of women with distinct postoperative RR trajectories. Differences among classes were evaluated using analyses of variance and chi-square analyses.
Results: Three distinct classes were identified as follows: RR <0.95 (37.9 %), RR ~1.00 (46.8 %), and RR >1.05 (15.3 %). Patients in the RR >1.05 class were more likely to have diabetes (p = 0.036), were more likely to have BC on their dominant side (p < 0.001), had higher RR ratios at the preoperative and 1-month assessments (p < 0.001), and were more likely to be diagnosed with LE (p < 0.001).
Conclusions: LCGA is a useful analytic technique to identify subgroups of women who may be at higher risk for the development of LE, based on trajectories of limb volume change after BC surgery.
Implications for cancer survivors: Assessment of preoperative and 1-month bioimpedance RRs may allow for the earlier identification of patients who are at higher risk for the development of LE.
Keywords: Bioimpedance spectroscopy; Breast cancer; Latent class analysis; Lymphedema; Resistance ratios; Upper extremity.