LINDAU, Germany—Cancers, revered researcher Harold Varmus told me today, are like snowflakes, each one unique. But cancers also belong to families, and members of those families share vulnerabilities—genetic weak spots that scientists are learning to target with increasing precision. That makes this a very exciting time in the long slog against the second leading cause of death in the U.S.

Varmus is here in Lindau, Germany for this week’s 65th Lindau Nobel Laureates Meeting, an annual confab at which Nobelists give lectures and meet with young scientists from around the world. Varmus shared his Nobel in 1989 with J. Michael Bishop for their work on retroviral oncogenes. Since then, Varmus has held medical power positions including director of the U.S. National Institutes of Health, president of Memorial Sloan Kettering Cancer Center in New York, director of the U.S. National Cancer Institute, and most recently, a faculty member at Weill Cornell Medical College.

I sat down today to talk to Varmus about our deepening understanding of cancer and how diagnosis and treatment will change in the era of precision medicine. Below is an edited recording of our conversation: