Table 3.

Optimal qualities of pathologic surrogates for survival following neoadjuvant therapy

Optimal qualities of pathologic surrogates for survival following neoadjuvant therapy
1)	Valid: Improvement in the surrogate outcome should correlate with improvement in overall survival, including in specific histiologic and molecular subgroups.
2)	Reflective: Surrogate outcome should reflect the biologic impact of treatment as well as the magnitude of the effect of the treatment on survival.
3)	Moderate frequency: Surrogate outcome should be sufficiently frequent to permit statistically relevant assessments using reasonable sample sizes, but sufficiently infrequent enough that improvement is attainable.
4)	Defined: Surrogate outcome should have an unequivocal definition.
5)	Feasible: Surrogate outcome should be easily and feasibly assessable with universally acceptable methods.
6)	Reproducible: Surrogate outcome should be reproducible with minimal inter-observer variability.