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Laboratory Diagnosis of Cancer (Ancillary Techniques -used when dx by…
Laboratory Diagnosis of Cancer
Definitive Diagnosis
Representative
Adequate
Properly preserved for necessary studies
Biopsy
Surgically resected tissue/organ
-Formalin for fixation
-Overnight paraffin block cut into thin slices
-H&E stain
incisional
(part of lesion) or
excisional
(entire lesion) biopsy
Core needle biopsy
-Stereotatic Core Biopsy (breast tissue)
-Core Needle in Prostate Cancer
Intraoperative by Frozen Section
-NO FORMALIN; must be fresh
-Preliminary diagnosis
-Use to:
-determine type or extent of surgery
-Benign vs. Malignant
-Resection adequacy
-Confirm metastatic disease
Cytology
(Dx via appearance of single or small groups of cells;
nuclear morphology
; more
difficult
than histological dx)
Exfoliative
-Cells spontaneously fall off (ex: pap smear, pleural fluid, sputum, urine, CSF)
Fine Needle aspiration
-Cells sucked up through needle; ultrasound guided (ex: ductal carcinoma of breast, thyroid)
Ancillary Techniques
-used when dx by morphology alone difficult
Anaplastic tumors (malignancy? tissue origin?)
Genetic/molecular changes?
Benign or malignant lymph process?
Flow Cytometry
:arrow_right:Forward scatter = SIZE
:arrow_upper_right:Side scatter = "internal complexity"
(multiple fluorescein tagged Ab can be used)
:cancer:
Leukemia
&
Lymphomas
(high discohesive cells)
NO FORMULIN :tumbler_glass:
Immunohistochemisry
(Abs to cell components)
EX:
p16
immunostain to dx Cervical Dysplasia
Cytogenetics
Molecular Diagnostics
-Dx malignancy
-Prognosis of malignancy
-Detect minimal residual disease
-Dx hereditary cancer risk
-Guiding therapy against specific oncoprotein drugs (personalized med)
FISH
(Fluorescence In Situ Hybridization)
can see translocation
PCR
Need to have:
-Probe
-Polymerase for DNA or Reverse Transcriptase for RNA
NGS
(Next Generation Sequencing)
-Tumor molecular profile
What genes mutated and active?
DNA Microarrays / Gene Chips
Gives quantitative RNA data (transcriptome) =
gene expression profiles for tumors
Liquid Biopsies
(from blood sample)
3 MAJOR APPROACHES:
Circulating Tumor Cells (
CTC
)
free floating in plasma or bone marrow
Cell Free DNA (
cfDNA
) released by necrotic tumor nuclei)
many tumors release this
Cologuard
FDA approved; looks for RAS mut. in fecal samples
Exosomes & Ectosomes
(membrane-bound microvesicles released into blood by neoplastic cells that contain mostly
mRNA
,
miRNA
& numerous cell
proteins
;
Macrophage Migration Inhibitory Factor (MIF)
checks for metastatic potential)
Used to make
diagnosis
or
analyze cancer genomics