[caption id="attachment_70763" align="aligncenter" width="500"] Freepix image[/caption] Cancer is one of the most complex and heterogeneous diseases known to medicine. Tumors can differ not only between patients but also within a single individual, with subclones evolving over time and influencing how the disease progresses or responds to treatment. Next-generation sequencing (NGS) has become a critical tool in oncology, helping researchers and clinicians unravel this complexity at the molecular level. By analyzing DNA and RNA at high resolution, NGS enables the detection of mutations, copy number changes, gene fusions, and expression patterns that shape tumor biology. This information provides insight into cancer drivers, mechanisms of resistance, and therapeutic targets. Importantly, it also supports precision medical oncology, where treatments are guided by the specific molecular features of a patient’s tumor rather than by one-size-fits-all approaches.