P3-07-30: Applying the Findings of the Z11 Trial to a UK Practice.
Authors: Chalmers CR , Mallon EA , Stallard S , Doughty JC , Wilson CR 
Published: June 2012

Introduction: The finding of a positive sentinel node is currently managed by further Level III axillary lymph node clearance (ALNC). The rationale behind this approach is that of local disease control, but there is little evidence that axillary lymph node clearance results in a reduction in axillary recurrence or in mortality. ALNC is however associated with increased morbidity (lymphoedema, nerve damage, reduced shoulder function) and significantly prolongs hospital stay. The Z11 trial suggests that ALNC following positive sentinel node biopsy does not result in lower axillary recurrence rates compared to the group in whom clearance was not undertaken and has obvious implications for evidence-based practice. The Z11 trial has strict inclusion criteria (T1/T2 tumour, breast conservation surgery) with all patients receiving adjuvant whole breast radiotherapy and systemic chemotherapy or endocrine therapy. For patients who do not meet the patient population of Z11, such as women undergoing mastectomy, the Sloane-Kettering predictive normogram provides an estimate of risk for residual axillary disease after positive sentinel node biopsy and the estimate of this risk may inform the clinical decision to clear the axilla based on individual cancer characteristics. Methods: Our population comprises both symptomatic and screening patients, with an axillary positivity rate of approximately a third. This study was undertaken to assess the impact that Z11 would have on our practice. Our prospectively maintained records were searched for ALNC patients treated between 2003 and 2011. We assessed the number of node-positive patients conforming to Z11 criteria and the number who demonstrated residual axillary positivity at clearance after a positive sentinel node. The axillary recurrence rate for this group after ALNC was recorded. We calculated the number of clearances that could have been avoided, and extrapolated the reduction in morbidity in lymphodema and nerve damage using the audited incidence of these complications in our institution. We calculated the financial cost saving in terms of theatre usage and hospital stay. In addition, we assessed whether the Memorial Sloane Kettering predictive normogram is useful in the prediction of residual axillary disease for the group of patients excluded from the Z11 cohort.

Results: 1601 patients underwent axillary staging. 65% of our patients with node-positive disease were identified pre-operatively with ultrasound and biopsy and proceeded directly to ALNC. Our overall axillary recurrence rate was low (&lt;1% at 5 years). 26% of our patients would not meet the criteria for Z11, predominantly due to the requirement for mastectomy. Of those that met the Z11 criteria, 60% had no further axillary disease at clearance and a further 25% demonstrated low volume (1-3 positive nodes) residual disease only. The Memorail Sloane Kettering normogram can be used in estimating risk of residual axillary disease in patients undergoing mastectomy.

Discussion: Using these criteria nearly 25% of axillary clearances in our population of breast cancer patients could be avoided with obvious cost savings both in terms of morbidity and finance, considerations that are important in planning our service for the future.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-07-30.