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M. Christie
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P3.04 - Poster Session/ Biology, Pathology, and Molecular Testing (ID 235)
- Event: WCLC 2015
- Type: Poster
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:
- Coordinates: 9/09/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P3.04-051 - Molecular Testing on Cell Blocks Formed From Bronchial Brush Tip Washings (ID 2334)
09:30 - 09:30 | Author(s): M. Christie
- Abstract
Background:
With the rapid growth of genotype guided targeted therapies, molecular testing is increasingly important for the routine work up in lung cancer. This testing is traditionally performed on biopsy specimens. Bronchoscopy is commonly performed for diagnosis of suspected lung cancer; and multiple sampling modalities are often combined to maximize diagnostic yield. Bronchial brushings are frequently reported to have the highest sensitivity, though the cytology smears generated from these brushings are rarely used for molecular analysis. The aim of this study was to assess the feasibility and accuracy of molecular testing performed on cell blocks (CB) formed from a brush tip wash (BTW).
Methods:
We retrospectively reviewed molecular testing performed on CB from BTW in patients undergoing investigation of peripheral lung lesions between January 2014 and March 2015. During bronchoscopy, brushings were performed and smears created. Following this, the brush tip was then washed in normal saline. This was repeated each time the peripheral lesion was sampled with the bronchial cytology brush. The fluid from the BTW was then processed into a formalin fixed paraffin embedded CB. Patients were included in the study cohort if molecular testing was attempted on the CB created from BTW. The CB specimens underwent molecular testing targeting regions on BRAF (exon 15), KRAS (exon 2,3,4), NRAS (exon 2,3,4), PIK3CA (exon 9. 20) and EGFR (exon 18, 19, 20, 21) genes by amplicon-based parallel sequencing using an Illumina MiSeq.
Results:
There were 22 patients in whom BTW CB was subjected to molecular testing. Results are summarized in figure 1. Figure 1 Figure 1. Results of molecular analysis In fifteen cases (68%) a CB was generated, and was successfully subject to molecular testing. Fourteen of these were adenocarcinomas, in which the frequency of detecting a mutation in any of the five assayed genes was 57% (8/14). This is similar to previous reports of molecular testing on adenocarcinoma from other sampling modalities, and suggests that BTW CB generally contain adequate tumour cells for testing. In seven cases, there was no diagnosis obtained from transbronchial lung biopsy, meaning BTW was the sole specimen available for molecular testing.
Conclusion:
Our results demonstrate that molecular studies can successfully be performed on cell blocks obtained from brush tip wash and that this may be the only sample that has adequate material for analysis. We suggest that brush tip washings be routinely created during bronchoscopy to maximize the likelihood of successful molecular testing.
