MKI67 and gastrointestinal stromal tumor: Interestingly, when comparing PD‐L1 expression in recurrent GISTs from patients treated with adjuvant imatinib and from those without, there was no significant difference, suggesting that adjuvant imatinib did not impact the regulation of PD‐L1, which matched the results of previous research.29 PD‐L1 expression was positively correlated with tumour size, tumour mitotic rate and Ki‐67 expression in 112 samples, but not in the 15 recurrent GIST samples (Figure 1B‐D).