- Is an algorithm necessary for the markers? For instance, if Pulmotype is run on two specimens and the same markers are positive/negative, would it result in the same call of squamous/adeno (which ever the case may be)? Once I do enough of these, the algorithm won’t be necessary. As these are entered as simply positive or negative and not a percentage, the answers will repeat.
- TTF-1 is necessary to confirm NSCLC primary as well adeno. I’m not willing to give it up. Why add 5 more markers instead of just adding p63 and CK 5/6?
- Can I order these markers individually without the algorithm?
- Why can’t I run these in-house?
- My homebrew works fine. I don’t have issues classifying NSCLC.
- I find it difficult to move to IHC markers I know nothing about, for what seems to be a small increase in benefit. What don’t we know about Trim29 for instance? I’m comfortable with what I know.
- When I read Pulmotype antibodies I sometimes see focal staining with adeno markers that contradict the Pulmotype differentiation call and vice versa. How should I interpret these cases where a focal staining pattern contradicts a more global staining pattern? How should I use Pulmotype in mixed differentiation or adenosquamous NSCLC?
- Is an algorithm necessary for the markers? For instance, if Pulmotype is run on two specimens and the same markers are positive/negative, would it result in the same call of squamous/adeno (which ever the case may be)? Once I do enough of these, the algorithm won’t be necessary. As these are entered as simply positive or negative and not a percentage, the answers will repeat.
- Pulmotype markers are entered into the algorithm as positive or negative. There are 32 possible combination of staining with these markers which occur with differing frequencies. The most practical approach to interpreting these combinations is to use the algorithm.
TTF-1 is necessary to confirm NSCLC primary as well adeno. I’m not willing to give it up. Why add 5 more markers instead of just adding p63 and CK 5/6
- TTF-1 alone is not specific for concluding that a tumor shows adeno differentiation. A common “home brew” approach combines TTF-1 and p63 and requires TTF-1 to be positive while p63 to be negative to accurately determine adeno differentiation status. Our paper validating Pulmotype compared it with TTF-1/p63 and showed Pulmotype to be more sensitive and equally specific. The accuracy of TTF-1/p63 was ~80% whereas that of Pulmotype was ~90%. Our results with TTF-1/p63 were BETTER than prior publications using smaller numbers of samples. Therefore we believe Pulmotype is a superior test.
- TTF-1/p63 was shown in our study to be relatively specific and therefore if it gives an interpretable result, is not a bad assay. CK 5/6 did not add to this combination (was redundant with p63) in our study. Other assays, including adding other additional markers to TTF-1 and p63, do not have published evidence supporting their use and therefore should be used cautiously in our opinion.
Can I order these markers individually without the algorithm?
- No. These markers are best run in a central lab that has performed equivalency studies to ensure performance comparable with the published manuscript. In addition for histotype determination, we believe they should be used as validated in the Modern pathology publication using the Pulmotype algortihm. Therefore, we offer the Pulmotype test as tech only, and not as individual markers.
Why can't I run these in-house?
- Several antibodies in the assay are not available commercially and Clarient does not currently offer certain Pulmotype antibodies individually.
- We believe that the reference lab based approach, using centralized staining and interpretation by the local pathologist (e.g. tech only), assures the highest standards of quality control for staining while maintaining close involvement of the local pathologist in interpreting the case.
My homebrew works fine. I don’t have issues classifying NSCLC.
- In many NSCLC cases, available sample is very limited and or morphology is disrupted compelling the use of IHC aids for helping with determination of histotype. Comparative studies have clearly highlighted that pathologists, even “experts” in NSCLC, are inconsistent in interpreting histotype even when sample is not limiting (Histology Matters: Individualizing Treatment in Non-Small Cell Lung Cancer; Neal, Joel, W.; “The Oncologist” 2010;15:3–5). Historically, “homebrew” assays have been used from helping determine histotype. Their use is based upon anecdotal evidence of their accuracy without systematic study of how they should be used, or defining appropriate controls for their specificity. Pulmotype brings a new level of evidence-based medicine to the histotype call through the publication of its sensitivity and specificity in a study of greater 1,100 patients from three independent institutes.
I find it difficult to move to IHC markers I know nothing about, for what seems to be a small increase in benefit. What don’t we know about Trim29 for instance? I’m comfortable with what I know.
- We screened hundreds of antibodies to identify the subset we believe is optimized for differentiating histotype. The test is backed by a peer-reviewed publication that used over 1,100 samples to validate its relationship with outcome. This provides a level of evidence that is unprecedented in the literature for histotype determination.
When I read Pulmotype antibodies I sometimes see focal staining with adeno markers that contradict the Pulmotype differentiation call and vice versa. How should I interpret these cases where a focal staining pattern contradicts a more global staining pattern? How should I use Pulmotype in mixed differentiation or adenosquamous NSCLC?
- Many NSCLC tumors display mixed differentiation showing areas of adeno intermixed with squamous cell differentiation. This can vary from a very small fraction of a tumor to a large component compelling the diagnosis of adenosquamous NSCLC in some cases (~0.4-4% of tumors). IHC markers of differentiation will highlight these areas and could potentially confuse the diagnosis if not considered in the context of the larger impression of the available material. Pulmotype does not replace pathologist judgment in assessing the dominant differentiation type (or lack thereof) of a tumor. The markers are useful for clarifying cell type differentiation when morphologic assessment is difficult and should be interpreted in the context of other clues to the dominant biology of the tumor.