Stunned, Wojcicki called her primary care doctor, who was equally surprised and suggested she repeat the scan. She texted her sister Janet, a professor of pediatrics and epidemiology at the University of California San Francisco, and told her the report showed bone cancer. “She said, 'I did it at a questionable radiology center because I wanted a quick MRI, so I’m going to repeat it,'” says Janet, who connected her sister to a radiologist friend. Even then, “I was joking with my friend that we didn’t think it was possibly real.”

The second scan showed the same thing, and doctors believed that the cancer found in Wojcicki’s bones had spread there from another source. “Sure enough, it was cancer, and it was metastatic,” says Wojcicki's husband, Dennis Troper, a project management director at Google. “It was a bomb dropping in the room.” 

Wojcicki had lung cancer, which kills more than 125,000 Americans each year, more than any other cancer. It wasn't on her radar: She had never been a smoker. She was healthy, active, and only in her early 50s. Yet people like Wojcicki, who don't fit the classic picture of someone with lung cancer, are increasingly developing the disease. While people with a smoking history make up the bulk of lung cancer cases and deaths, up to 20% of new diagnoses in the U.S. and worldwide are in nonsmokers. By the time most of these cases are diagnosed, they have already advanced and spread to other organs, at which point the disease is difficult or, often, impossible to treat.