In patients treated with ALND, bilateral arm measurements will be obtained using the Perometer (Model 350 NT Perometer, Per-System) circumferential arm measurements with elastic tape taken at 4-cm intervals from the wrist to the shoulder & the L-Dex U400 (Impedimed, Brisbane, Australia) for bioimpedance measurements. Measurements will be performed at baseline (prior to surgery), post-operatively (after surgery) & at scheduled timepoints of 6 months, 12 months, 18 months, & 24 months after surgery for a total of 2 years. For a patient who is diagnosed with lymphedema at ≥ 13 months after surgery, surveillance will continue for an additional 12 months after [lymphedema] diagnosis, & total surveillance time may exceed 2 years. Height & weight will be obtained for each patient at baseline & at each scheduled visit for the purpose of calculating BMI. All patients will complete the ULL-27 (upper limb lymphedema) quality-of-life questionnaire at baseline & at each scheduled visit.

Study requirements which include arm measurements, height and weight and completion of a questionnaire at a single long-term follow-up timepoint, will be explained to the patient

Patients will also be counseled about blood draws, which will include withdrawal of up to 20 mL of blood. Patients who are eligible and agree to participate will sign a consent form. Arm measurements, height and weight, blood draw (if applicable), and baseline questionnaire will be performed at first contact if possible, or at a follow-up scheduled visit prior to surgery.

Pts treated with ALND, bilateral arm measurements will be obtained using the Perometer (Model 350 NT Perometer, Per-System) circumferential arm measurements with elastic tape taken at 4-cm intervals from the wrist to the shoulder & the L-Dex U400 (Impedimed, Brisbane, Australia) for bioimpedance measurements. Measurements will be performed before surgery, post-operatively & at timepoints of 6,12,18, & 24 months after surgery for 2 years will be obtained using the Perometer (Model 350 NT Perometer, Per-System) for bioimpedance measurements. Pts who have not yet developed lymphedema by 2 years, an additional measurement at approx 3 years post-surgery will be performed. If pt is diag with lymphedema at the 3-year visit, she will be asked to continue on study for an additional year. Pts treated with SLNB alone, following re-consent, a long-term follow-up volumetric arm measurement will be obtained using the perometer & circumferential arm measurements at a minimum of 2 years post-surgery.

as defined by perometry using rigorous measurement protocols. Bilateral arm measurements will be obtained using the Perometer (Model 350 NT Perometer, Per-System) and the L-Dex U400 (Impedimed, Brisbane, Australia) for bioimpedance measurements.