Emerging technologies for monitoring breast cancer response to neoadjuvant chemotherapy: a systematic scoping review

Neoadjuvant chemotherapy (NACT) is increasingly used in early breast cancer treatment and responses are highly variable. Accurate monitoring of tumour response is crucial for enabling precise surgical de-escalation, yet current methods are inadequate. This systematic scoping review explores emerging technologies for predicting, monitoring, and diagnosing pre-operative breast cancer response to NACT.

A search of Embase, Medline, PubMed, and Cochrane databases was conducted until January 26, 2024. Studies investigating ability to detect tumour response during or after NACT, and prior to surgery, were included, and placed into 12 technology categories. Those investigating novel technologies were further categorised by Technology Readiness Level.

From 2497 studies, 1329 met the inclusion criteria. 479/1329 (36 %) investigated conventional imaging; 19 % (253) investigated MRI, 5 % (64) mammography/ultrasound, 0.5 % (6) computed tomography, 0.4 % (5) digital breast tomosynthesis. Established technologies included gene panels (134/1329; 10 %) and post treatment core biopsy 35/1329; (3 %). 107/1329 (8 %) of studies developed nomograms based on routine clinical investigations, and 493/1329 (37 %) correlated established biomarkers e.g. Ki-67 with pathological response. 81 studies (6 %) addressed novel technologies, such as circulating nucleic acids (49/81), diffuse optical imaging (17/81), and elastography (15/81). A Technology Readiness Assessment revealed that all were between Technology Readiness Level 2 (Invention and Research) and 6 (Large Scale).

The majority of current research activity focuses on optimising existing technologies which may never provide the step change in diagnostic accuracy required to advance surgical de-escalation. Research activity should be focused on identifying effective novel technologies and driving translation into the clinical environment.