ROCK HILL, S.C. — Kashyap Patel looked forward to his team’s Friday lunches. All the doctors from his oncology practice would gather in the open-air courtyard under the shadow of a tall magnolia tree and catch up. The atmosphere tended to the lighthearted and optimistic. But that week, he was distressed.

It was 2021, a year into the coronavirus pandemic, and as he slid into a chair, Patel shared that he’d just seen a patient in his 40s with cholangiocarcinoma, a rare and lethal cancer of the bile ducts that typically strikes people in their 70s and 80s. Initially, there was silence, and then one colleague after another said they’d recently treated patients who had similar diagnoses. Within a year of that meeting, the office had recorded seven such cases.

“I’ve been in practice 23 years and have never seen anything like this,” Patel, CEO of Carolina Blood and Cancer Care Associates, later recalled. Asutosh Gor, another oncologist, agreed: “We were all shaken.”