C. D. Ness1, I. Buccimazza2, B. Sartorius3, S. S. Maharaj1 1Physiotherapy Dept. Health Sciences, UKZN 2Breast Unit, Dept. of General Surgery, Nelson R Mandela School of Medicine 3UKZN,Discipline of public Health, Bio-medical and statistics (UKZN)
Introduction: Breast Cancer Related Lymphoedema (BRCA Ly) is clinically diagnosed once a 2cm circumferential difference is measured between the affected and unaffected limb, equating to 200ml limb volume difference (LVD).
Aim(s):
1. To determine at what limb volume difference (LVD) the lymphatic system starts to fail (pre-clinical) by using Bio Impedance Spectroscopy (BIS).
2. To determine whether this correlates with a different circumferential/LVD measurement?
Methods: This was a prospective study comprising 60 consenting, female BRCA survivors, post adjuvant therapy at the Provincial Oncology Clinic KZN. We included all consenting women up to 18 months post radiation and excluded patients with bilateral BRCA or other primary cancers, previous mantle field radiation. Data collected included epidemiological information extracted from the patient files, circumferential limb measurements with a tape measure and electrical impedance in the subcutaneous space using the LDEX-U400 BIS unit. The study was approved by the UKZN Bio-ethics Research Committee BE250/010
Results: BRCA Ly cut off at ≥200ml performed fairly well as a diagnostic tool for true abnormality based on BIS sensitivity of 67% and specificity of 93% ( AUC 0.8). Using a cut off of ≥100ml based on BIS abnormality scores, performed better with sensitivity but specificity was reduced to 69% (AUC 0.84). Optimal break point in actual continuous volume at169ml performed best in terms of diagnostic capability for abnormal/normal BIS, PPV of 71% and NPV of 93%, 95% CI: 0.86-0.99.
Conclusion: This study shows that the lymphatic systems optimal breakpoint for lymphatic system failure is 169ml LVD, which corresponds significantly to abnormal BIS readings. Using a clinical threshold of 100ml/1cm LVD provides 100%NPV but only 52% PPV versus NPV of 93% and PPV of 71% if 169ml LVD is used as a threshold for intervention of lymphatic drainage therapy. Early intervention of risk reducing strategies for patients improves quality of life, function and reduces costs for patients and stakeholders in a low resource setting.
