Axillary lymph node ultrasound and fine needle aspiration in pre-operative breast cancer staging

Routine ipsilateral axillary ultrasound of patients with breast cancer has been performed in our Trust since September 2008. Fine needle aspiration (FNA) is then performed on nodes when they fulfil local criteria for possible nodal metastasis, in line with recent National Institute for Health and Clinical Excellence (NICE) guidance.

We present an audit of these results that prompted a change in local criteria for FNA.

Patients who had entered the treatment pathway and undergone axillary surgery between October 2008 and May 2009 were identified from multidisciplinary team (MDT) meeting records. We investigated whether axillary ultrasound was always performed, and if criteria for FNA yielded sensitivities and specificities that compared favourably with the literature.

Records were available for 133 female patients with invasive breast cancer, 89% (118 patients: 67 screening, 51 symptomatic) of whom underwent axillary ultrasound. Axillary ultrasound sensitivity was 49% (23 of 47: symptomatic 58% (18 of 31), screening 31% (5 of 16)), and specificity was 93% (66 of 71: symptomatic 80% (16 of 20), screening 98% (50 of 51)). Axillary FNA sensitivity was 88% (14 of 16: symptomatic 85% (11 of 13), screening 100% (3 of 3), and specificity was 100% (2 of 2).

Combination of ultrasound and FNA had an overall sensitivity of 45% (21 of 47), and a specificity of 96% (68 of 71).

Ultrasound had a relatively high false negative rate (22%, 26 of 118) and therefore led to low rate of subsequent FNA. FNA had a low false negative rate (11%, 2 of 18).

These results, with literature review, have been used to alter local ultrasound guidelines for FNA. Further audit to validate these new guidelines is ongoing.