Lung Cancer Diagnosis and Classification

Question 1

How do cell pathologists contribute to molecular pathology?

Answer 1

They assess the sample quality for sequencing, mark the tumour area for an appropriate FISH assay, and correctly score and interpret molecular predictive assays like HER-2, ALK and PD-L1 IHC.

Question 2

How does size of sample impact the purpose for the sample?

Answer 2

Small biopsies are for diagnosis. Resections or whole organs or parts of organs are for curative purposes.

Question 3

As well as size of sample, what else do histo want from a sample?

Answer 3

Fresh sample, and the right site.

Question 4

Molecular tests need a minimum amount of tumour content to work. What does IHC require though?

Answer 4

A minimum number of tumour cells.

Question 5

When doing a PD-L1 ICH assay, how many viable tumour cells do you need?

Answer 5

100

Question 6

What do you need to identify tumour cells for IHC?

Answer 6

Know the assay and tissue well. avoid necrotic tissue

Question 7

Using IHC to test for ALK rearrangements doesn’t have a minimum of 100 cells like PD-L1 IHC. Why?

Answer 7

Just need enough tumour cells to see a positive result, don’t need a percentage. Will see a strong brown signal or you won’t. PD-L1 is more patchy

Question 8

If you’ve seen a dark brown stain for ALK IHC, how can you confirm a rearrangement?

Answer 8

FISH with break apart probes. Look for a split signal, or isolate red signal.

Question 9

When pathologists were surveyed about what makes their job difficult, what were the 3 most common answers?

Answer 9

83% - Lack of tumour content
42% - Lack of funding for staff for sectioning
33% - Lack of clinical information

Question 10

What’s the issue of a pathologist that causes them to do lots of tests? And what’s a negative result of that?

Answer 10

If they get a negative result for a stain, they feel like they need to do more stains until they do come to a diagnosis. But an extended IHC panel being pushed to meet turn around time will use up too much tissue. Leaving little for molecular tests.

Question 11

A pathologist should know what about each test like sanger and NGS?

Answer 11

The sample input requirements. Number of sections and thickness.

Question 12

If there’s enough tumour cellularity across a whole block/section what does not need to be done

Answer 12

No need to do a H&E and mark the section if it’s clearly enough.

Question 13

What should be specified by pathology when sending a section to genetics?

Answer 13

The tumour content

Question 14

What doing somatic tests, what might you need to be careful of when sending samples to genetics?

Answer 14

If you have a germline sample then don’t send that by mistake.

Question 15

What test often needs tumour and normal tissue?

Answer 15

Mismatch repair testing

Question 16

What’s the typical tumour content required for DNA NGS assays?

Answer 16

> 30% tumour content

Question 17

What samples are often retrieved from advanced lung cancer patients/

Answer 17

Small biopsies or cytology specimens such as pleural fluids or fine needle aspirates - These can be spun down and treated as a block

Question 18

What two tissue features can interfere with assays and should be ideally avoided?

Answer 18

Mucin and necrotic tissue

Question 19

When it comes to tumour content estimation, small specimens can lead to….

Answer 19

false negatives

Question 20

What do tumour cells look like typically in lung cancer?

Answer 20

Big epithelial cells with big nuclei

Question 21

Why should you not just look at cell area?

Answer 21

Because tumour cells are a lot bigger then lymphocytes, so you would largely overestimate the tumour cell content if you do it by area and not nuclei

Question 22

Where especially will lymphocytes outnumber tumour cells?

Answer 22

In lymph nodes, so be careful

Question 23

What are 3 elements responsible for the variation between observers calculating cellularity?

Answer 23

Inadequate definition of tumour cellularity.
Spatial heterogeneity of tissue.
Subjective character of morphological assessment.

Question 24

In a study comparing lung and colon tumour cell content estimates of 40-50 participants, what was the largest difference in estimations for the same sample?

Answer 24

66%!!!

Question 25

What had a big impact in the study comparing pathologists estimates of the same tissues?

Answer 25

Dense or scattered lymphocytic infiltrates or mucinous stroma.

Question 26

Do pathologists typically over estimate or under estimate tumour cell content? And why is this an OK thing?

Answer 26

They often under estimate, which is OK, because any negative results would be considered to possibly be false negatives and get repeated anyway.

Question 27

If you get 2 blocks from a core biopsy, the one with the highest neoplastic content should be conserved for which test? IHC or mutation testing?

Answer 27

Mutation testing.

Question 28

In a CRC sample EQA or 2016 and 2017, 31/228 labs did not take into account what?

Answer 28

That the sample provided had no neoplastic cells. So they genotyped the sample wrongly as wildtype.

Question 29

What’s the best method for delineating the tumour area on a slide?

Answer 29

Precise tumour shape outlining with a dotted line got the highest proportion of neoplastic cells.

Question 30

Reporting of mutation testing should include what?

Answer 30

A statement of the estimated tumour cell content and whether it was adequate. If it was too low, state it could be a false negative and that another sample would be best.

Question 31

ctDNA tests use what techniques typically?

Answer 31

ddPCR or allele specific PCR or NGS

Question 32

ctDNA tests may represent what?

Answer 32

All sites of disease better

Question 33

ctDNA can be in which forms?

Answer 33

shed DNA or exosomes bearing DNA

Question 34

As well as tumour nuclei content, what else could also be given as a percentage?

Answer 34

Necrosis %

Question 35

Be aware of what can be done to _______ your interpretation of your results

Answer 35

Be aware of what can be done to validate/confirm your interpretation of your results

Question 36

Molecular test are ordered when?

Answer 36

Reflexly by a pathologist at the time of diagnosis OR requested by an onocologist at an MDT

Question 37

When a cancer recurrence happens, what should you do?

Answer 37

Acquire a new biopsy

Question 38

For lung cancer which 2 genes are standard to be mutation screened?

Answer 38

EGFR and BRAF

Question 39

For lung cancer, which 3 genes are standard to be tested by IHC?

Answer 39

ALK, ROS1, PDL1

Question 40

What genes are tested by fusion analysis with lung cancer that are important in other cancers?

Answer 40

NTRK fusions