tumor purity
The percentage of cancer cells relative to normal cells in a tissue sample. Essential metric for interpreting genomic test results and variant detection sensitivity.
Full Definition
Tumor purity refers to the proportion of malignant cells present in a tissue sample relative to contaminating normal cells, stromal cells, and immune infiltrates. This metric is crucial for precision oncology because low tumor purity can reduce the sensitivity of variant detection, particularly for mutations present at lower allelic frequencies. Most genomic profiling platforms require a minimum tumor purity threshold (typically 20-30%) for reliable results. Pathologists assess tumor purity through microscopic examination, and computational methods can estimate purity from sequencing data. Understanding tumor purity helps editors interpret why certain tests may fail or produce inconclusive results.
Usage
Usage note: Express as percentage; distinguish from tumor burden which refers to total amount of cancer in the body.
In Context
- "The specimen demonstrated 70% tumor purity, meeting the threshold for comprehensive genomic profiling." — Pathology assessment
- "Low tumor purity (15%) precluded reliable detection of low-frequency variants." — Laboratory limitation note