Conno Christou doesn’t believe in leaving things to chance. He monitors his sleep with a Whoop band, compares it with an Oura ring, and undergoes nearly 100 biomarker tests annually. For four consecutive years, he had been conducting this yearly bloodwork, adhering to the protocols of longevity experts like Peter Attia and Rhonda Patrick. He fine-tuned his supplements, his circadian rhythm, and his protein intake. At 35, while building his second company, he was as deeply immersed in cutting-edge health research as anyone he knew. His most recent checkup, in 2025, showed everything was excellent. “It was the best I’d had in years,” he recalls. Then, following a workout, his arm began to swell. Initially, he dismissed it. A week passed before he consulted a doctor, who discovered two blood clots in his veins and scheduled surgery. However, the pre-operative exams changed everything. A doctor returned to the room and told him the procedure was off. “We see an 11-by-11-by-8 centimeter mass behind your sternum,” the doctor said. A biopsy confirmed something Christou had never even considered. He had an aggressive, fast-growing form of non-Hodgkin’s lymphoma—a rare diagnosis affecting roughly one in 420,000 people, caused by a random genetic mutation unrelated to lifestyle, diet, or stress. The tumor had only existed for about three months. In three more weeks, it would have reached stage four. “Lucky in my unluckiness,” Christou told this editor from his home in Athens, where he lives part-time. “It was only found because I went in for something else entirely.”

What followed was a lesson in the constraints of the medical system, and in what a determined patient can accomplish with the tools now available. His first oncologist, a renowned specialist, recommended the milder of two available chemotherapy regimens. Christou scheduled his first infusion three days out. Then, the night before, he sought a second opinion. That second doctor didn’t hesitate. He recommended the more aggressive regimen—continuous in-hospital infusion, cycling every three weeks over six months—citing Christou’s specific pathology. The lighter treatment carried roughly a 60% success rate for his condition. The aggressive one raised that number to around 85%. Two world-class doctors. Completely opposite recommendations. “As founders, we hold the wheel,” Christou says about the tendency of many people to accept what they are told, and why more should not. “You hear many things. You don’t have to follow the first advice.”

He didn’t simply follow the second physician’s advice either. Over the next two days, he gathered 12 opinions in total—tapping into his professional network, reaching out to hematologists and oncologists in the U.S. and abroad, calling in every favor he could. Eleven to one favored the harder path. He took it. The decision, he says, didn’t feel brave so much as logical. When the stakes are existential, you collect data. Over six months of treatment, Christou approached chemotherapy the way he approached building a company: as a marathon of sprints, each with a finite cycle, each week filled with data points. He had completed a mandatory 25-month military service in Cyprus at age 18, and he drew from that experience as well. He was going to be a good soldier, he told himself. Trust the process. Six cycles. Get through it. He wore his Whoop throughout, and found it remarkably accurate at predicting the days his immune system would bottom out, sometimes flagging them before symptoms appeared. He kept a symptom journal using voice transcription, logging every shift, every side effect, every medication and counter-medication. He narrowed his focus to three variables: sleep, nutrition, and, first and foremost, psychology. (“It moves the needle more than anything,” said Christou. “I never asked ‘why me’—not once. That question has no useful answer.”)

He fed all of it—blood results, scan data, wearable output, journal entries—into Claude. He’s far from alone in turning to chatbots for medical guidance. A public opinion poll released in March found that a third of American adults now use them for health information and advice. Stories accumulating online suggest that for some patients, AI is delivering what the system couldn’t. Experts urge caution; Danielle Bitterman, clinical lead for data science and AI at Mass General Brigham, has told the New York Times in recent months that general-purpose chatbots are frequently wrong and “have not been thoroughly evaluated” for personalized diagnoses. Christou doesn’t disagree. “It didn’t replace the doctors,” he says, but it “helped me ask the right questions.”

For a condition as rare as his—one an oncologist might see once a year—access to a model that had absorbed the full body of medical literature was, he says, simply not the same as a Google search. That distinction proved critical at the end of treatment. His final PET scan—the imaging used to detect active disease—came back ambiguous. His oncologist began discussing a second line of therapy, potentially radiotherapy, near his heart and lungs. It was an alarming development. Christou again did his homework. He read that for this specific lymphoma, the false-positive rate on end-of-treatment PET scans is around 60%—a statistic that still astonishes him. “It’s 2026,” he says. “Sixty percent.”

He fed all three of his PET scans and his MRI into Claude, which flagged a known but easily overlooked phenomenon: in patients under 40 recovering from this type of lymphoma, the thymus gland can reactivate after chemotherapy, showing up on imaging as what appears to be active disease. Given his age, his specific scan characteristics, the model put the probability of that explanation at roughly 90%. He sought three more opinions. The fourth doctor confirmed it: thymus rebound. There was no active disease. No radiotherapy was needed. He was clear.

Christou is still processing what the last year has meant—for his health, how he works, and how he thinks about time. He built Keragon, his current company, before any of this happened; it’s an AI-powered platform that helps medical practices automate their administrative operations. But going through the system as a patient has given him new perspective. He watched nurses and doctors buried under tasks that had nothing to do with care. He received the same chemotherapy protocol as an 80-year-old woman, the side effects managed through a cascading chain of additional drugs, each causing problems of their own. He says he’s certain that we will look back at this era of treatment and cringe. He takes Sundays off now, mostly. He tries to be present—at lunch with friends, at home with his dog, in conversations that might once have felt like a distraction from work. A VC friend told him something years ago that he said he kept replaying during treatment: Be happy now. He says it’s among the hardest things to do and yet he finally appreciates its importance. He says he’d be happy to talk to anyone going through something similar to share notes, compare experiences. He seems to mean it. “It’s not happening in 10 years,” he says of what AI can already do for patients willing to use it. “It’s happening today.”