Optimizing pathology sample submissions

Only a small amount of quality tumor is required to run Prolaris. Several factors can affect the quality and usability of the sample. Learn more about how you can optimize the sample selection and reduce test cancellations.

• Number of positive cores
  A greater number of positive cores increases the likelihood of sample acceptance because the 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 <10% involvement may not meet the 0.5mm length requirement. This can be remedied by combining tumor from multiple cores (cores range in length from 5 mm to 15mm).
• Tissue remaining in the block
  The procedure for cutting tumor sections to diagnose cancer varies greatly. Most labs cut between 2 and 6 levels. The more levels cut, the less amount of tissue remains in the block. Many labs discard the intervening sections between the sections used for diagnosis. The percentage of the core remaining after slides are cut for diagnosis varies from 0% (no tissue) to 50%.
• Quality of sample
  In addition to 0.5mm continuous tumor length requirement, samples must also contain 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.
• Proper fixative
  Samples must be fixed in a formalin-based fixative. To confirm an alternate fixative, please contact Customer Service.