PD-L1 expression in cell-blocks of non-small cell lung cancer: The impact of prolonged fixation.

Our results show that fixation time influences the performance of 22C3 LDT on CBs. Thus, we recommend that the fixation time of cytological materials be carefully checked, especially when PD-L1 testing is delayed until the oncology request. Indeed, delays in tissue processing and paraffin embedding may lead to sub-optimal performance of PD-L1 staining on CBs.