The testing process for new drugs and treatments is rigorous, requiring multiple steps so that researchers have plenty of chances to monitor risks and spot side effects. Drugs and treatments undergoing testing usually go through four phases:
Phase I: Used to research how to set up larger trials. A phase I trial is usually very small, requiring just a few volunteers, and focuses on basic safety and efficacy, as well as how to administer the drug and the best dose to test.
Phase II: Organized to systematically test safety and effectiveness.
Phase III: Set up to compare safety and effectiveness against existing drugs and treatments, phase III trials are very large, usually with thousands of participants. They're held at multiple locations, participants are randomly assigned to receive either the new treatment or standard treatment, and processing all the data usually requires several years. The majority of trials breast cancer patients enter are phase III trials.
Phase IV: This involves a follow-up study, usually conducted after the drug or treatment receives FDA approval, focusing on monitoring long-term safety and efficacy.
A drug that's in a phase III trial has been tested on more patients and subjected to more scrutiny for possible side effects than a drug in a phase I or II trial, so it's usually best to opt for the latest phase available.
