MKI67 and neoplasm: In clinical practice and research, different approaches can be used to monitor tumour responses during NACT: (1) clinical exam (most commonly used), (2) dynamic changes in tumour size as measured by imaging, (3) sequential biopsy of the tumour to evaluate change in biomarkers (often proliferation marker Ki67) and (4) molecular biomarkers in blood samples drawn over the time course of treatment [10, 11].