used specifically for these effects (Juhl, 2010), although little research has been published on this topic. In addition, the type of surgical procedure, the individual surgeon performing the procedure, and the use of robotic instruments are variables that affect the duration of the resection and the resulting tissue ischemia in the resection specimen. Although some information related to the number and types of drugs given before and during an operation may be available in clinical records, such as the anesthesia report, it is uncommon to have these data available to a biorepository. The committee does not know whether or how many specimens in the JPC repository are annotated with data related to perioperative variables that may be pertinent to molecular research on the molecular profiles of tissue samples.
Perhaps the most common preanalytic variable with an important effect on results of analytic tests, such as immunohistochemical staining, is the time that elapses after surgical removal of tissue until it is stabilized with fixation or freezing (cold ischemia time). The process of structural and biochemical tissue degradation occurring during this time is termed autolysis. The amount of time can be substantial, ranging from minutes to hours, and is rarely recorded in the pathology report. It may cause gain or loss of signal on molecular analysis, depending on the molecular entity in question. An analysis done without knowledge of the duration of the time to fixation and without an intrinsic control within the same specimen that can serve as a reference (for example, surrounding normal tissue that is known to express or not to express the molecule constitutively) may be misleading or even completely incorrect (Spruessel et al., 2004).
Storage conditions or duration may compromise specimen quality.
Oxidation occurs in both blocks and cut sections, but it is much greater on cut surfaces exposed to room air. Thus, tissue blocks stored at temperatures below the melting point of paraffin yield cut sections that show little deterioration of immunohistochemical signal compared with freshly embedded controls for as little as 2 years or as long as 25 years (Engel and Moore, 2011). RNAases are active even in FFPE tissues. For many antigens, immunoreactivity has been shown to deteriorate more rapidly if specimens are stored as cut sections rather than whole blocks; both the time line and the magnitude of the effect are antigen-dependent.
On a crude level, paraffin blocks that have been stored under conditions that do not include climate control may lead to melting of paraffin blocks in warm weather or destruction from other causes. Gross specimens, albeit formalin-fixed, may undergo dehydration, fungal contamination, and putrefying deterioration when stored under conditions that expose them to environmental extremes. All those issues have affected specimens held by the JPC at some point over the course of the repository’s history (Asterand, 2008).