Essential evidence includes medical records confirming your cancer diagnosis through pathology reports, imaging studies, and treatment documentation that establish the type, stage, and progression of disease. Testimony about your talc use patterns and timeline—including when you started using products, how frequently you applied them, where on your body you used them, and approximately when you stopped—forms the foundation of exposure evidence even without physical product containers. Pharmacy or store records if available, photographs showing products in your home from family albums or social media, witness statements from family members who remember your product use and can corroborate your testimony, and any communications with doctors about talc exposure during diagnosis or treatment all strengthen your claim. While keeping actual products helps demonstrate exactly which formulations you used, it’s not required as testimony about consistent use patterns, brand loyalty, and purchasing habits often suffices to establish exposure, particularly when combined with other corroborating evidence and expert testimony about the products’ composition during the relevant time period.