Fig. 4.

Location of residual tumours and percentage that remained undetected Location of residual tumours in a 32 resection specimens (control group) that were detected accurately by endoscopic biopsy after neoadjuvant chemoradiotherapy and b 27 resection specimens (study group) that remained undetected by endoscopic biopsy after neoadjuvant chemoradiotherapy, according to biopsy type used during clinical response evaluation (CRE). The number in each cell represents the tumour regression grade (TRG): TRG 1, no residual tumour; TRG 2–4, residual tumour. c Percentage of residual tumour cells present in the mucosa or submucosa that remained undetected during CRE in the study group. The results of further quantification are shown in the most superficial layer containing residual tumour cells in the mucosa or submucosa. The number in each cell in the lower part represents the percentage of vital residual tumour cells present.