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Christopher Harreld



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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): Christopher Harreld

      • Abstract
      • Slides

      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

      Conclusion

      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.

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