Does preoperative axillary staging lead to overtreatment of women with screen-detected breast cancer?

Abstract

To determine the impact of preoperative axillary ultrasound staging in a screen-detected breast cancer population. Ultrasound and needle biopsy staging results alongside reference standard sentinel lymph node biopsy and axillary lymph node dissection were extracted retrospectively from the unit's computer records between 1 April 2008 and 31 March 2015. Axillary staging was compared with final histopathology and treatment. Of the 215,661 screening examinations performed, 780 invasive cancers were diagnosed, which had preoperative axillary staging data, of which 162 (20.7%) were node positive. Thirty-six (4.6%) had a heavy nodal burden (three or more nodes). Ninety (11.5%) had an abnormal axillary ultrasound and axillary biopsy of which 54 were positive for cancer (33.3% of the node positive cases) and triaged to axillary lymph node dissection avoiding a sentinel lymph node biopsy. Of these 22 (40.7%) had neoadjuvant treatment, and 32 (59.3%) proceeded directly to axillary lymph node dissection. The sensitivity of axillary ultrasound and biopsy to detect women with a heavy nodal burden (three or more nodes) was 41.7% (15 of 36); however, 17 (53%) of the 32 women with a positive axillary biopsy had a low burden of axillary disease (two or fewer positive nodes) at axillary lymph node dissection, the mean number of nodes obtained was 14.6. Significant numbers of women are being potentially overtreated or denied entry into positive sentinel node: adjuvant therapy only versus adjuvant therapy and clearance or axillary radiotherapy (POSNOC) because of routine preoperative axillary staging.