Prostate Needle Biopsy Samples

Prolaris only requires a small amount of quality tumor to run the test

If you are submitting a sample from a prostate needle biopsy please include 7 consecutive slides, each 3 – 5 microns in thickness with tumor that is at least 0.5mm in length.

 

Several factors can affect the quality of a sample:

Number of positive cores

A greater number of positive cores increases the likelihood of sample acceptance, since tumor can be combined from multiple cores. With a single positive core, sample acceptance is most correlated with the percentage of tumor in the core (the higher the %, the more likely the acceptance).

 

Percentage of core that is positive

Cores with less than 10% involvement may not meet the 0.5mm in length requirement. This can be overcome by combining tumor from multiple cores (cores range in length from 5mm to 15mm).

 

Tissue remaining in the block

The procedure for cutting tumor sections to diagnose cancer varies greatly by lab:
• Labs vary in how deeply they face the block. These initial sections are all discarded.
• Most labs cut between 2 and 6 levels. The greater the number of levels cut, the smaller the amount of tissue remaining in the block.
• Many labs discard the intervening sections between the sections they use for diagnosis.
• The percentage of the core remaining after slides are cut for diagnosis varies from 0% (no tissue) to 50%.

Quality of Sample

Samples must be at least 0.5mm in length and 75% or greater tumor glands of macro dissectible tumor tissue. Often, prostate needle biopsies contain small foci of invasive cancer intermixed with normal tissue, which makes macro dissection of tumor difficult. Below are examples of acceptable and non-acceptable samples.

Fixative

The sample must be fixed in a formalin based fixative.

 

Recommendations to Optimize Prolaris Testing

Fixation
• Record fixation time
• Use adequate volume of formalin (min 10:1 ration of formalin : tissue)
• Fix biopsies for 6-18 hours
• Use formalin within its expiration date
Processing
• Use high quality reagents for tissue processing
• Replace reagents regularly, per mfg guidelines
Embedding
• Use low-melting point paraffin wax for embedding (optimal, use considerations in very hot months)
Sending Slides or Blocks
• Cut fresh sections
• Use disposable blades to prevent cross-contamination
Shipping
• Pack samples with ice pack to prevent warping

Prolaris Post-Prostatectomy Samples

When submitting post-prostatectomy samples for Prolaris testing, the submission of tumor blocks is preferred over tumor slides.

Tumor Block Submissions

Block Selection

Select formalin-fixed paraffin-embedded tumor block(s) with the greatest amount of prostate tumor. Ideally, tumor size should be at least 5mm in length on the diagnostic H&E slide.

Tumor Slide Submissions

Select formalin-fixed paraffin-embedded tumor block(s) with the greatest amount of prostate tumor. Ideally, tumor size should be at least 5mm in length on the diagnostic H&E slide.
To obtain optimal results, please adhere to the following criteria for preparing slides:

  • Cut and label 7 consecutive unstained slides as follows:
    • Slide #1: 3-5 micron thickness on a charged slide
    • Slides #2 – #6: 10 micron thickness on uncharged slides
    • Slide #7: 3-5 micron thickness on a charged slide
  • Do not bake slides or use adhesives
  • Please number slides in order of cutting
  • Place ordered slides in slide holder

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