In 2005, violinist Treesa Gold became concerned when she began experiencing weight gain, hair loss and acne. She saw a doctor, who told her, “You’re 24 and healthy. Stop being paranoid.”

Unsatisfied with this response, she saw an endocrinologist a few months later. After reviewing her bloodwork, he ordered a CT scan, which revealed a 13-centimeter adrenal gland tumor. Treesa was diagnosed with adrenocortical carcinoma. A surgeon...