Genetic mutations typically involve three categories of genes:
- Oncogenes (genes that promote the transformation from a normal cell to a cancer cell),
- Tumor suppressor genes (TSG), and
- DNA repair genes.
Some genes are capable of multitasking. For example,
BRCA1,
BRCA2, and
p53 are TSG while at the same time also mediating damaged DNA repair work.
Cancer does not happen in a day; rather, it can take years for a normal cell to be transformed to become a cancer cell. While DNA mutations as a consequence of environmental carcinogens tend to be random, a "triple whammy" of mutations that lead to cancer involves the deregulation of oncogenes, tumor suppressor genes, and DNA repair genes all occurring at the same time. The cellular outcomes of such molecular chaos are manifested as unstoppable cell growth followed by the metastatic invasion of neighboring healthy cells, tissues, and organs.
Table 1. Summary of Representative Oncogenes, Tumor Suppressor Genes, and DNA Repair Genes.| Gene Categories | Examples |
| Oncogenes | EGFR, HER2, KRAS, HRAS, PI3K |
| Tumor suppressor genes | p53 (TP53), Rb, BRCA1, BRCA2, MADR2 |
| DNA repair genes | p53(TP53), BRCA1, BRCA2, RAD1, CHEK1 |
