MKI67 and cancer: In this scenario, only rHb was found to differentiate Ki67-positive from Ki67-negative cancer, with lower values of rHb occurring for Ki67-positive cancer (p-value 0.01, Wilcoxon ranked sum test, Fig. 4a; see Additional file 1: Table S5 for values of all DOT physiological parameters of Ki67-positive and Ki67-negative cancer groups).