Liquid biopsies and cancer detection | Max Diehn, M.D. Ph.D.

**Peter Attia, MD** (0:11)
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Now, without further delay, here's today's episode.
My guest this week is Max Diehn. Max is a Professor of Radiation Oncology, Vice Chair of Research and Division Chief of Radiation and Cancer Biology at Stanford University.
Max is a co-founder of Foresight Diagnostics, a precision medicine company developing novel liquid biopsy tests for measurement of minimal residual disease. He's also the co-founder of CyberMet, a company that applies data science for biomarker discovery. Max also consults and advises a number of companies in similar spaces. Max's current research involves the development of novel methods for detecting circulating tumor DNA in the blood of cancer patients. He also works to understand cancer cells by identifying molecular pathways and genes associated with disease, and he's interested in uncovering biomarkers that can predict response to therapy or predict patient survival and return of disease as early as possible, which is something we'll get into in the discussion so you can understand why it's so important to predict recurrence as soon as it happens.
Clinically, Max is a radiation oncologist and he specializes in lung cancer. He manages a broad clinical research portfolio and he focuses on improving these personalized therapies for patients with lung cancer. In this episode, we talk about a lot of things. First of all, Max and I were also classmates in medical school, so we catch up a little bit on that and we talk about his background and how he became interested in liquid biopsies. We go into great detail here on sensitivity, specificity, negative predictive value, positive predictive value. These are things that everybody needs to understand if they want to be smart on diagnostics and if they want to understand cancer screening. Talk about why these things are important and in particular, how they play into cancer screening, especially when it comes to understanding prevalence and pre-test probability. We spend some time talking about lung cancer, which is the number one killer for both men and women.
And it's not just a smoker's disease. Remember, 15% of people who die of lung cancer have never smoked a cigarette in their life. So this is an important cancer, whether or not you are a smoker or not. From there, we dive really deep into liquid biopsies, the landscape, the history, the possible future of liquid biopsies. For me, this was the high point of this interview. In fact, in preparing for this interview, I myself had to get a lot smarter in liquid biopsies. Certainly, I know more about them than the average bird, and I've spent a lot of time looking at them over the past two years. But I think in this episode, we get a lot more granular around the nuances of the different ways in which, not just we can look at circulating tumor cells versus cell-free DNA, but when looking at cell-free DNA, what are the different methods that we can use to predict if a cancer is present? In other words, how can we look at the actual genes from the actual cancer that we know we're searching for versus in a screening situation when we don't know the gene that we have to look for other clues? So we talk about these cell-free DNA, RNA signatures. We talk about methylation patterns. We talk about the importance of knowing mutation information. We talk about the difference in some of the screenings being approved by the FDA versus those that are being permitted to use for patients without FDA approval formally. There's a lot packed into this episode, but it is truly one of the most important subjects given the difficulty in treating cancer when it becomes advanced. So without further delay, please enjoy my conversation with Max Diehn.
Hey Max, thanks so much for making time today. So wonderful to see you again. It's been a lot of years, huh?

**Max Diehn, M.D., Ph.D.** (4:14)
It's been a long time. Actually, I can't remember the last time we saw each other, but we started together in medical school at Stanford, but then finished a little bit different times. I think it's been a while since we saw each other.