What is Tumor Profiling?
Tumor profiling is different from hereditary genetic testing. It doesn’t give information about a person or their risk for cancer. It gives information about the genes specifically in the cancer cells. A pathologist can look at the characteristics of the cancer cells to help guide treatment.
Tumor profiling can look at thousands of genes in the cancer cells in a tumor. Specific genes or combinations of genes may tell a doctor which drugs or combination of drugs may work better than others. It may also help predict whether a cancer is more likely to have a recurrence (come back again) or metastasize (when cancer spreads to other organs different from the original location).
Types of Molecular Tumor Testing
Many types of gene alterations can occur in cancers. The four main types include:
- Single nucleotide variants (SNVs), also known as point mutations. SNVs result from a base substitution at one nucleotide. These may result in a change in the amino acid sequence of the encoded protein (missense mutation) or a premature truncation of the protein (nonsense mutation).
- Small duplications of consecutive nucleotides, insertions or deletions involving one or a few nucleotides, or more complex mutations involving simultaneous deletions and insertions of one or a few bases (indelsa). These types of mutations may be “in-frame,” resulting in the addition or subtraction of amino acids in the protein, or can cause a “frameshift,” typically resulting in a premature truncation of the protein.
- Exon or gene copy number changes. Exon copy number changes include large duplications or deletions encompassing entire exons and affecting the functional domains of the protein. Gene copy number changes include amplifications or deletions of the entire gene.
- Structural variants (SVs) or large structural anomalies of genetic material including translocations or inversions that result from breakpoints between multiple chromosomes or within a single chromosome. These often result in fusion genes and associated fusion proteins.