The fittest founder in the room got cancer. Here’s how he used AI to fight back.

Conno Christou leaves nothing to chance. He tracks his sleep with a Whoop band, compares it to an Oura ring and has almost 100 biomarkers checked every year. He had taken the annual blood test for four years in a row, following the protocols of longevity researchers like Peter Attia and Rhonda Patrick. He was optimizing his supplements, his circadian rhythm and his protein intake.

At age 35, when he started his second company, he was as up to date on the latest health research as anyone he knew. His last check, in 2025, was green across the board. “It was the best I’ve had in years,” he says.

Then, after a workout, his arm swelled.

At first he didn’t think much about it. A week passed before he saw a doctor, who discovered two blood clots in his veins and scheduled surgery. But the preoperative exams changed everything. A doctor walked back into 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 what Christou had never considered before. He had an aggressive, fast-growing form of non-Hodgkin’s lymphoma – a rare diagnosis that affects about 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 another three weeks it would have reached stage four.

“Lucky for my bad luck,” Christou told this editor this week from his home in Athens, where he lives part-time. “It was only found because I was going for something completely different.”

What followed was an education about the limits of the medical system, and what a determined patient can do about them with the tools now available.

His first oncologist, a renowned specialist, recommended the lighter of the two available chemotherapy treatments. Christou booked his first infusion three days later. He then asked for a second opinion the night before.

That second doctor didn’t hesitate. He recommended the more severe regimen – continuous infusion in the hospital, every three weeks for six months – citing Christou’s specific pathology. The lighter treatment yielded a success rate of approximately 60% for his presentation. The aggressive version brought that number to about 85%. Two world-class doctors. Diametrically opposite recommendations.

“As founders, we are in the driver’s seat,” Christou says of many people’s tendency to accept what they’re told – and why more people shouldn’t. “You hear a lot of things. You don’t have to follow the first advice.”

He also did not choose to simply follow the second doctor’s advice. Over the next two days he collected a total of twelve opinions. In doing so, he leveraged his professional network, contacting hematologists and oncologists in the US and abroad, calling in whatever favors he could. Eleven to one voted in favor of the harder path. He took it. The decision, he says, didn’t feel brave so much as it felt logical. He was already a data-driven person, and now the stakes felt existential to him.

Over six months of treatment, Christou approached chemotherapy the way he approached building a business: as a marathon of sprints – each with a finite cycle and each week filled with data points. He had completed mandatory 25-month military service in Cyprus at the age of 18 and he also borrowed from that experience. He would make a good soldier, he told himself. Trust the process. Six cycles. Get through it.

He wore his Whoop all the time and found it remarkably accurate at predicting the days when his immune system would hit rock bottom, sometimes marking them before symptoms arrived. He kept a symptom diary using voice transcription, recording every shift, every side effect, every medication and counter medication. He narrowed his focus to three variables: sleep, nutrition and, primarily, psychology. (“It moves the needle more than anything,” Christou said. “I never asked ‘why me’ – not once. That question has no useful answer.”)

He entered it all – blood results, scan data, portable output, diary entries – into Claude. He is far from the only one turning to chatbots for medical guidance. A poll The March publication found that a third of American adults now use them for health information and advice. The stories online accumulation suggests that AI is delivering for some patients what the system could not.

Experts urge caution; Danielle Bitterman, clinical lead for data science and AI at Mass General Brigham, told the New York Times in recent months that general-purpose chatbots often wrong and “have not been thoroughly evaluated” for personalized diagnoses.

Christou disagrees. “It didn’t replace doctors,” he says, but “it helped me ask the right questions.”

For a condition as rare as his—one that an oncologist might encounter once a year—accessing a model that had absorbed the entire body of medical literature simply wasn’t the same as a Google search, he said.

The model proved to be crucial at the end of the treatment. His last PET scan – the imaging used to detect active disease – turned out to be equivocal. His oncologist began discussing a second line of therapy, possibly radiation therapy, near his heart and lungs. It was an alarming development.

Christou did his homework again. He read that for this particular lymphoma, the false positive rate on PET scans at the end of treatment is about 60% – a statistic that still amazes him. “It’s 2026,” he says. “Sixty percent.”

He entered Claude into all three of his PET scans and his MRI, which revealed a well-known but easily overlooked phenomenon: In patients under 40 who recover from this type of lymphoma, the thymus gland can reactivate after chemotherapy, showing up on imaging as active disease. Given his age and his specific scan characteristics, the model estimates the probability of that explanation at approximately 90%.

He asked for three more opinions. The fourth doctor confirmed it: thymus rebound. There was no active disease. No radiotherapy was required. He was clear.

Christou is still unfolding what the past year has meant, for his health, how he works and how he thinks about time. He built Keragon, his current company, before all this happened; it is an AI-powered platform that helps medical practices automate their administrative activities.

But going through the system as a patient has given him a new perspective. He saw nurses and doctors buried under tasks that had nothing to do with healthcare. He was given the same chemotherapy protocol as an 80-year-old woman, with side effects controlled by a chain of additional medications, each causing their own problems. He says he’s confident we’ll look back on this era of treatment and cringe.

He now usually takes Sundays off. He tries to be present – ​​at lunch with friends, at home with his dog, in conversations that might once have been a distraction from work. A VC friend told him something years ago that he said he kept repeating throughout treatment: be happy now. He says it’s one of the hardest things to do, yet he finally realizes its importance.

He says he’d love to talk to anyone who’s going through something similar, to share notes and compare experiences. He seems to mean it.

“It won’t happen in ten years,” he says of what AI can already do for patients who want to use it. “It’s happening today.”