Cancer Diagnosis Program | Biorepositories and Biospecimen Research Branch

Search BRD Papers

Association Between Formalin Fixation Time and Programmed Cell Death Ligand 1 Expression in Patients With Non-Small Cell Lung Cancer.

Author(s): Kawachi H, Fujimoto D, Yamashita D, Fukuoka J, Kitamura Y, Hosoya K, Sato Y, Nagata K, Nakagawa A, Tachikawa R, Date N, Sakanoue I, Hamakawa H, Takahashi Y, Tomii K

Publication: Anticancer Res, 2019, Vol. 39, Page 2561-2567

PubMed ID: 31092453 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study compared the effects of formalin fixation duration (12-24 h or 96-120 h) on immunohistochemistry (IHC) analysis of programmed cell death ligand 1 (PD-L1) expression in non-small cell lung cancer (NSCLC) tissue specimens using two different assay systems. Resected tumor specimens from 54 NSCLC patients (median age 70.9 y, 35 males, 19 females) were split and immediately fixed in 10% buffered formalin for 12-24 h or 96-120 h and then immediately processed for paraffin embedding (details not provided). Tissue sections (4 μm thick) were cut from the FFPE blocks, deparaffinized, rehydrated, and stained for PD-L1 using two assay systems (22C3 and SP263) on an automated staining platform. Slides were evaluated by two independent pathologists. Tumor cells were considered positive when the cell membrane was partially or completely stained. Tumor proportion scores were determined as the percentage of PD-L1-positive tumor cells in the overall section (estimated in increments of 5% except in the case of 1% positivity) with 1%, 25%, and 50% set as the cut-off values to determine agreement.

   Summary of Findings:

   For the 22C3 assay, mean PD-L1 tumor proportion scores were comparable between specimens fixed for 12-24 h and those fixed for 96-120 h (18.8% and 16.3%, P=0.277) and the overall percentage of agreement at the expression cut-offs of 1%, 25%, and 50% were 85%, 94%, and 91%, respectively. Results were discordant among 14 matched pairs with eight having a higher proportion score after 96-120 h of fixation and six having higher scores after fixation for 12-24 h. Similarly, mean PD-L1 tumor proportion scores using the SP 263 assay were comparable between specimens fixed for 12-24 h and those fixed for 96-120 h (16.2% and 17.6%, P=0.560) and the overall percentage of agreement at the expression cut-offs of 1%, 25%, and 50% were 80%, 94%, and 93%, respectively. For the 16 discordant results, higher proportion scores were observed after fixation for 12-24 h in three matched pairs and after fixation for 96-120 h in 13 cases. When considering all cases with a tumor proportion score ≥1%, mean scores were not significantly different between specimens fixed for 12-24 h and those fixed for 96-120 h using the 22C3 assay (32.6% and 32.1%, P=0.231) or the SP263 assay (31.3% and 33.4%, P=0.659). Overall percentage of agreement for PD-L1 immunostaining at the cut-offs of 1%, 25%, and 50% were 92%, 89%, and 81% for the 22C3 assay, respectively; and 96%, 89%, and 86% for the SP263 assay, respectively. Among discordant results when fixation durations were compared, specimens fixed for 12-24 h had higher proportion scores compared to corresponding matched specimens fixed for 96-120 h in six of the eight cases for the 22C3 assay and in three of six discordant cases for the SP263 assay.

   Biospecimens

   • Tissue - Lung

   Preservative Types

   • Formalin

   Diagnoses:

   • Neoplastic - Carcinoma

   Platform:

   Analyte	Technology Platform
   Protein	Immunohistochemistry

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Immunohistochemistry Specific	Targeted peptide/protein	PD-L1
   Biospecimen Preservation	Time in fixative	12-24 h 96-120 h

   View more