Download Validation and Interpretation in Cellular Pathology Sarah Dean

VALIDATION AND
INTERPRETATION IN CELLULAR
PATHOLOGY
Sarah Dean
LECTURE OVERVIEW
Types of Samples
 Types of Stains
 Interpretation of results
 Clinical vs Research
 How do we ensure those results are valid?

Use of controls
 UK NEQAS scheme


Types of analyses/statistical tests
LECTURE OVERVIEW
Types of Samples
 Types of Stains
 Interpretation of results
 Clinical vs Research
 How do we ensure those results are valid?

Use of controls
 UK NEQAS scheme


Types of analyses/statistical tests
TYPE OF SAMPLES
TYPES OF STAIN

H&E

Special Stains

IHC
Biotin
Biotin – Conjugated to Peroxidase
Avidin
Avidin Biotin Complex (ABC)
INTERPRETATION
Can be considered subjective
 Pathologist must be highly trained

Types of interpretation:
 Scoring of IHC results
 Grading of a cancer (H&E)
 Presence of a marker (positive or negative?)

What about computer software interpretation?
SCORING OF IHC STAINED SLIDES

E.g. Oestrogen receptor status in breast cancer
SCORING OF IHC STAINED SLIDES

Prognostic
vs
Predictive
EXAMPLES FOR YOU TO TRY
CANCER GRADING

E.g. Prostate cancer
PROSTATE CANCER H&E
PRESENCE OR NOT OF A MARKER

E.g. Amyloid protein

Congo red stain

Apple birerefringence
COMPUTER SOFTWARE INTERPRETATION?

Your thoughts?
THE EVIDENCE?
THE EVIDENCE?
LECTURE OVERVIEW
Types of Samples
 Types of Stains
 Interpretation of results
 Clinical vs Research
 How do we ensure those results are valid?

Use of controls
 UK NEQAS scheme


Types of analyses/statistical tests
CLINICAL VS RESEARCH INTERPRETATION

What do you think the differences are?

“In medicine and statistics, gold standard test refers to a
diagnostic test or benchmark that is the best available under
reasonable conditions. It does not have to be necessarily the best
possible test for the condition in absolute terms.”

Clinical?

Research?
STANDARD CLINICAL INTERPRETATION
EXAMPLES IN CELL PATH

Cancer Grading


Each cancer has it’s own grading system
Immunohistochemical Staining

Biomarkers used in clinical lab have defined scoring
systems:
Allred
 0-3+ for HER2 in breast cancer
 H scoring

Biomarker dependent
 Disease dependent


Are considered the “gold standard”
HOW DO YOU DECIDE IN A RESEARCH
SETTING?
New IHC Biomarker
Has someone published with it?
YES
NO
In the same disease?
YES
Is their a
suggested method
from the
manufacturer?
NO
Is the expected
staining pattern
similar?
Great- then use
their method*
YES
Great- then use
their method*
NO
YES
Great- then use
their method*
Use a similar
biomarker scoring
system for your
disease
*Check their staining quality and use of controls
NO
Use a similar
biomarker
scoring system
for your disease
LECTURE OVERVIEW
Types of Samples
 Types of Stains
 Interpretation of results
 Clinical vs Research
 How do we ensure those results are valid?

Use of controls
 UK NEQAS scheme


Types of analyses/statistical tests
HOW DO WE ENSURE VALID RESULTS?

How do we ensure scientific “vigour”?

Why Bother???
Antibody Validation
Bordeaux J. et al. 2010 biotechniques.com
USE OF CONTROLS
How do we prove a negative result?
 Example: A breast cancer sample is stained for 3
different biomarkers using IHC. The sample is
negative for all 3.

WHAT CAN BE USED AS A POSITIVE
CONTROL?

A piece of tissue known to contain that biomarker
E.g. Amyloid
 Infectious agent


Cell line controls
With known expression
 Over-expressing


We can “prove” a negative result beyond
reasonable doubt.
UK NEQAS SCHEME



How do we ensure validity AND standardisation
between clinical labs?
http://www.ukneqas.org.uk/images/Flash/FlashPl
ayer_High.asp
http://www.ukneqasiccish.org/assessmentprocedure/ an example.
LECTURE OVERVIEW
Types of Samples
 Types of Stains
 Interpretation of results
 Clinical vs Research
 How do we ensure those results are valid?

Use of controls
 UK NEQAS scheme


Types of analyses/statistical tests
EXAMPLES OF TESTS

Does the new method give the same results as
the current?
Cohen’s Kappa- level of agreement
 Spearman’s or Pearson’s


Is this new method of prognostic value?
Retrospective study
 Kaplan Meier survival plot
 Correlation with tumour grade/stage


Does this new method predict response to
therapy
 Retrospective
 Clinical
Trials
study
LECTURE OVERVIEW
Types of Samples
 Types of Stains
 Interpretation of results
 Clinical vs Research
 How do we ensure those results are valid?

Use of controls
 UK NEQAS scheme


Types of analyses/statistical tests