DNA sequencing has provided data to indicate that cancer cells may contain tens of thousands of somatic mutations, only some of which confer a growth advantage to a cancer cell. How do scientists describe and categorize these recently discovered populations of mutations in cancer cells?

Answer: Categorizing somatic mutations in cancer cells is essential for several reasons: it helps scientists identify specific genetic changes responsible for cancer development, allows for a better understanding of the molecular mechanisms driving cancer progression, and aids in the identification of potential biomarkers for cancer diagnostics and prognostics. Somatic mutations in cancer cells are classified into two main types: driver mutations, which directly confer a selective growth advantage to the cancer cell and contribute to cancer development, and passenger mutations, which do not offer any selective advantage and have little or no impact on the cancer's progression. This classification helps researchers focus their research on driver mutations to develop new and effective cancer therapies.