<p>Retrospective clinical studies are critical in interventional oncology (IO), offering insights by analyzing existing data. They are cost-effective, time-efficient, and invaluable for exploring real-world treatment trends, long-term effects, and rare diseases. Retrospective studies provide critical support for hypothesis generation, post-marketing surveillance, and addressing ethically or logistically challenging questions unsuitable for prospective or randomized controlled trials (RCTs). To maximize their utility, retrospective studies must ensure robust data quality, clear objectives, advanced statistical methods, and transparency. Despite challenges like biases and limited causal inference, their ability to complement RCTs and other types of prospective trials help to close crucial gaps in evidence generation, which makes them indispensable for research in the rapidly evolving field of interventional oncology.</p>