Table 1.

Main variable factors affecting the preanalytical phase of FFPE sample processing

Processes	Persons in charge of the process	Preanalytical variable factors
Pre‐fixation process	Clinicians (persons who collect specimens)	Time from the cessation of blood flow to the removal of tissues (warm ischemic time) Time from the removal of tissues to their fixation (cold ischemic time) Size of tissues
Fixation process	Pathologists Pathology technologists	Composition of the fixative (i.e., concentration, buffered action, and pH of solution) Time and temperature of formalin fixation Ratio of the volume of fixatives to tissue volume during formalin fixation Treatment methods to penetrate tissues (i.e., immersion, injection, or acceleration by microwaves)
Post‐fixation process	Pathologists Pathology technologists	Conditions for decalcification (i.e., avoidance of acid decalcification) Tissue processor type and the frequency of replacement of the reagents used in the machine Conditions for dehydration and clearing (i.e., the types of reagents, temperature, and time used) Conditions for paraffin immersion (i.e., the type of paraffin, temperature, and time used)
(Post‐FFPE process)	Pathology technologists	Storage of FFPE blocks (the duration and condition) Storage of unstained FFPE slides (the duration)

Abbreviation: FFPE, formalin‐fixed paraffin‐embedded.