Imaging performance in guiding response to neoadjuvant therapy according to breast cancer subtypes: A systematic literature review

- 15 observational studies examined imaging performance for measuring response during NAC.
- Evidence to conclude on the preferred imaging technique per BC subtype is lacking.
- 18FDG-PET/CT seems to be preferred in ER-negative/HER2positive BC over MRI.
- MRI and 18FDG-PET/CT are promising in both triple negative and HER2-positive BC.
- Consensus should be reached on: interval time, cut-off values, and pCR definitions.

Monitoring therapeutic response to neoadjuvant chemotherapy(NAC) is likely to improve NAC effectiveness in breast cancer(BC). Imaging performance seems to vary per tumour subtype(by ER and HER2 status), therefore we performed a systematic review on subtype specific imaging performance in monitoring NAC in BC.Studies examining imaging performance in predicting pathologic complete response(pCR) during NAC in BC subtypes were selected. Per study, negative- and positive predictive value, sensitivity(se) and specificity(sp), AUC and accuracy were derived.Fifteen/106 articles were included. Inter-study variability was revealed in: monitoring interval, response and pCR definitions. In ER-positive/HER2-negative BC, 181F FDG-PET/CT showed se/sp of 38%-89%/74%-100%, MRI showed se/sp of 35%-37%/87%-89%. In triple negative BC, 181F FDG-PET/CT showed se/sp of 0%-79%/95%-100%. 181F FDG-PET/CT showed in ER-positive/HER2-positive BC se/sp of 59%/80% and in ER-negative/HER2-positive 27%/88%.Evidence on imaging performance in monitoring NAC according BC subtypes is lacking. Consensus should be reached in: definitions of pCR, response and monitoring interval before starting well-designed studies.