Table 2.

Comparison of main characteristics of neoadjuvant and adjuvant trials

Parameter	Neoadjuvant trials	Adjuvant trials
Definition	Treatment given before surgery	Treatment given after surgery
Sample size	Smaller	Larger
End points	Response rates and duration (pCR, EFS)	Relapse and survival (DFS, overall survival)
Time taken to complete	Months	Years
Costs	Lower	Higher
Advantages	Tumour downstaging—that is, converting a previously unresectable, locally advanced breast cancer to an operable tumour Enables early assessment of response to treatment Response-guided therapeutic planning is possible Enables comparison of the characteristics of pretreatment and post-treatment tumour samples (in those without a pCR), which might facilitate biomarker discovery, prognostication, patient stratification, and assessment of responses to therapy	Designed to increase the chance of long-term survival Quality-of-life questionnaires can be used to assess the long-term effects of treatment in multiple domains
Disadvantages	Local tumour control might be delayed Complicates pathological assessments and staging In some circumstances, duration of drug exposure is shorter, which might reduce its effectiveness Less long-term safety information is available Potential for selection of resistant clones owing to relatively high disease burden at the time of systemic treatment	Risk of exposing a large number of patients to treatment that is more toxic and/or no more (or even less) effective than the current standard of care Precludes assessment of response to systemic treatment and, thus, does not enable response-guided treatment planning

DFS, disease-free survival; EFS, event-free survival; pCR, pathological complete response.