Repurposed & Off-Label Drugs in Cancer: Understanding the Evidence Hierarchy
Executive Summary Repurposed drugs—existing medications studied for new indications—are increasingly discussed in cancer communities. Some show biological plausibility , others generate early clinical signals , but very few reach high‑quality evidence standards required to change clinical practice. The biggest source of confusion is the mixing of evidence levels . Cell studies, animal models, case reports, and randomized trials are often presented as equivalent. They are not. This guide: Defines each level of evidence Explains what conclusions can and cannot be drawn from each Shows why promising signals often fail to translate into real-world benefit Helps readers separate scientific uncertainty from false certainty 1. What Are Repurposed and Off‑Label Drugs? Repurposed Drugs Medications originally approved for one condition but studied for another (e.g., antiparasitic, metabolic, or anti-inflammatory drugs explored in oncology). Off‑Label Use Legal prescribing of an approved drug ...
