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Anne Marie Quinn
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P2.09 - Pathology (ID 174)
- Event: WCLC 2019
- Type: Poster Viewing in the Exhibit Hall
- Track: Pathology
- Presentations: 1
- Now Available
- Moderators:
- Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
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P2.09-23 - PD-L1 Expression of Paired Primary Resected Non Small Cell Carcinoma and Metastatic Lymph Node Fine Needle Aspirates (Now Available) (ID 2640)
10:15 - 18:15 | Author(s): Anne Marie Quinn
- Abstract
Background
Small biopsy or cytology samples may present with a different level of PD-L1 expression compared to resected samples (which usually entail scoring of a much greater number of cells) resulting in relatively increased or reduced tumour proportion scores (TPSs). Many PD-L1 results are based on cytology fine needle lymph node aspirates (FNLNAs), encompassing analysis of metastatic disease and the substitution of cytology for histology samples. We compared the PD-L1 TPS of metastatic FNLNAs with that of resected non small cell carcinoma.
Method
The pathology archive at Wythenshawe Hospital was searched for cases with adequate material over a period spanning 2010-2016. The Ventana SP263 PD-L1 clone was used to stain blocks select from 50 resected NSCCs and matched FNLNA cell blocks from each individual, along with a fresh H&E and negative PD-L1 control section.
Result
Four of the cell block sections were inadequate for TPS assessment. The remaining 46 cases comprised 21 adenocarcinomas, 3 large cell carcinomas, 1 large cell neuroendocrine carcinoma, 1 atypical carcinoid tumour, and 20 squamous carcinomas. 34 cell block PD-L1 TPSs (68%) were in broad agreement with the corresponding resection block TPS, based on cut-off levels of 1% and 50%. Of the 12 (32%) cases in which differences occurred, 6 (50%) reflected an increase in TPS from resection to FNA, while 6 reflected a decrease causing a change in therapeutic cut-off. Nine of the FNLNAs were sampled after the resection, favouring the presence of recurrent disease.
TABLE 1. PD-L1 expression of resections versus FNLNAs across TPS categories Resection Tumour Proportion Scores n, (%)
FNLNA Tumour Proportion Scores n, (%)
0 / <1%
1 - 49%
≥ 50%
p
0 / <1% 1 - 49% ≥ 50% p Total n = 46
12 (26)
15 (33)
19 (41)
16 (35)
7 (15)
23 (50)
0.14 Median age at diagnosis (yrs)
63 64 64 62 69 64 Adenocarcinoma
Squamous ca.
Othera
2 (4)
7 (15)
3 (7)
8 (20)
6 (11)
1 (2)
10 (22)
8 (17)
1 (2)
0.132 2 (4)
10 (22)
4 (9)
5 (11)
2 (4)
0 (0)
13 (28)
9 (20)
1 (2)
0.035 Discrepant cases n = 12
1 (8)
9 (75)
2 (17)
4 (33)
2 (17)
6 (50)
a Includes large cell carcinoma, large cell neuroendocrine carcinoma, atypical carcinoid
The majority of metastatic TPS FNLNAs are in broad agreement with a primary resected carcinoma TPS. FNLNAs tended to score less in the 1-49% category, possibly due to limits of cellularity. In addition to heterogeneity of expression, sampling of recurrent rather than residual disease may contribute to discrepancies.