Current practice and surgical outcomes of neoadjuvant chemotherapy for early breast cancer: UK NeST study

Neoadjuvant chemotherapy (NACT) is increasingly being used to treat early breast cancer, and offers several advantages, including reducing the extent of breast and axillary surgery, and providing an in vivo assessment of tumour sensitivity to treatment^1–4. Clinical trials have identified tumour subgroups with high rates of pCR. A pCR can be achieved in 45–90 per cent of human epidermal growth factor receptor 2-positive (HER2+) tumours and triple-negative breast cancer (TNBC), but the rate in oestrogen receptor-positive (ER+)/HER2-negative (HER2–) breast cancer remains below 10 per cent^3,5. Historically, increasing pCR rates following NACT have not translated into more breast-conserving surgery (BCS), but more recent data suggest that NACT can result in surgical downstaging⁶.

NACT use in the UK appears inconsistent, as highlighted by a recent prospective audit⁷. Although UK guidelines suggest considering NACT in patients with HER2+ cancers and TNBC, detailed guidance does not exist⁸. Furthermore, it is unclear whether pCR rates in routine clinical practice reflect those observed in trials, and whether tumour downstaging influences surgical decision-making beyond the trial setting. Moreover, there remains a lack of consensus on whether definitive surgery should aim to excise the original or post-treatment tumour footprint, as highlighted in a recent UK survey⁹, in which 24 per cent of centres stated that their routine practice was to excise the original tumour footprint rather than carry out response-adapted surgery.

This prospective study aimed to determine surgical decision-making in the breast and axilla and pCR rates in routine clinical practice following NACT for early breast cancer.