Latest / Common Sense Health / ctDNA: The Cancer Discovery Nobody's Talking About
Transcript
- Stephen: Hello. Let's talk about a blood test that sounds a little bit sci-fi-y but is very much real life and somehow still isn't as well known as it probably should be. Imagine you're trying to work out whether there's a smoldering fire behind a wall. Now the classic approach is either you wait until you actually see the smoke creeping out, which is a bit late, or you take a hammer to the plaster and you have a proper look. So that's basically scans and biopsies. Useful, sometimes essential, but not exactly subtle. Now, imagine another option. You don't smash anything, you don't wait for smoke, you take a quick sample of the air coming out from under the door and test it for microscopic soot. If you detect soot, something's burning. If you don't, you can probably breathe a little easier. Now that's the basic promise of CT DNA testing. CT DNA stands for circulating tumor DNA. And the idea is surprisingly straightforward once you hear it in normal English. Your body is constantly renewing itself. Cells are dying off and being replaced all the time. Now, when cells die, tiny fragments of DNA and cellular bits end up circulating in the bloodstream. If someone has a tumor or even tiny remnants of a tumor after treatment, those tumor cells can also shed DNA fragments into the blood. And the modern lab methods can sometimes detect those fragments and basically say, hang on, this DNA looks like it came from tumor tissue. Now, here's where it gets, I think, a little bit more interesting. Some tests like Naturiya's ⁓ tumor-informed approach, don't just go fishing for generic cancer signals, they try to look for the patient's actual tumour fingerprint, meaning they're not looking for any old weird DNA, they're looking for DNA that matches what was found in the original tumour. So instead of guessing from a distance, you're tracking something personalised, like having a sniffer dog trained on one person's specific scent, rather than just hoping it barks at anything vaguely suspicious. Now, this is why people get excited about this test, because it can, in some cases, give you a sense of tumour burden and recurrence risk with a simple blood draw. No scanners, no radiation, no waiting months for the next appointment to see if anything has changed. Just blood in, information out. So why isn't everyone in their neighbourhood talking about this? The short answer is medicine doesn't just want information. Medicine wants information that tells you what to do next and proves that doing the next thing actually helps people live longer or better. Now, this is the big sticking point. CT DNA can be very good at being an early warning system, but an early warning only helps if you've got a clear plan of what to do when the alarm goes off. DNA is positive, but your scan is still clean. You're suddenly in this awkward gray zone. Do you start treatment earlier? Do you intensify surveillance? Do you do more imaging? Do you wait different cancers, different stages, different treatment pathways? The right answer isn't always obvious and the evidence for exactly how to act is still evolving in a lot of settings. And that's why guideline bodies and big systems have often been cautious about re-routing use outside certain situations and clinical trials. It's not necessarily that the test is useless, it's that this predicts risk is not the same as this improves outcomes when we act on it. Now, let's talk about cost because yes, cost is also absolutely part of it, but it's not just the price of the test. There's the reimbursement side. If funding and insurance coverage are inconsistent, usage becomes inconsistent. Clinicians are less likely to order something routinely if it might land the patient with a nasty bill or a fight with an insurance company. Then there's what I call the domino effect cost. A positive CT DNA result can trigger more scans, more appointments, obviously more anxiety and sometimes earlier treatment. Again, that might be the right move in some cases, but it's a bigger resource commitment and health systems tend to move slowly when a new test creates downstream decisions that aren't fully standardized yet. And then there's reliability. And I want to be precise here because people hear reliability and think it means it doesn't work or something along those lines. That's not what I mean. The reality is that not all tumors shed CT DNA equally. Some cancers shed a lot into the bloodstream. Others shed very little. If the remaining disease is tiny or sitting in a place where it doesn't release much DNA into the circulation, you can get a negative result even when something is technically there. a negative result can be reassuring, but it's not a magic force field. It can be wrong. Now on the flip side, a positive can be a very strong signal, but it can also create that difficult moment of right. We've detected something at a molecular level. Now, what do we do today that we wouldn't have done otherwise? And I think there's another reason this isn't more well known. It's not really a general population screening test. This usually comes into play for people who already had a cancer diagnosis and treatment, and you're trying to monitor for minimal residual disease or recurrence risk. That's a much smaller audience and it lives in oncology clinics and trials rather than public health leaflets and on good morning TV. So where do I land on it? I mean I think CT DNA is one of those technologies that will look completely obvious in hindsight. Like of course we should be able to monitor cancer at a molecular level instead of waiting for it to become big enough to show up clearly on a scan. the adoption curve is slow because the final hurdle isn't whether we can detect it, it's whether acting on it in each specific cancer context clearly improves outcomes enough to justify the cost, the complexity and the potential ⁓ over-treatment sometimes. And if you're thinking, well this sounds like the same story we see with loads of biomarkers, you're not wrong. Because here's the bigger principle and it matters whether we're talking about ctDNA cholesterol fractions thyroid hormones inflammation markers or anything else Data without context can make smart people do daft things. It really is that simple So that's why I always insist on interpreting bloods in the context of the way the person's eating be it Ketogenic or carnivore or low-carb or whatever your baseline physiology can shift your reference point points can shift and if you interpret everything for a one size fits all lens you can end up chasing ghosts or missing the actual story. Now CT DNA is powerful because it's personalized but even then the interpretation has to be joined up with the full clinical picture. The cancer type, the stage, the treatment plan, the timeline, symptoms, imaging and the human being that's actually attached to that blood sample. So yes it's fascinating, yes it's promising and yes it probably deserves to be more widely understood even if we're still in the stage of working out exactly how to use it in the most helpful and obviously least harmful way. So if you like this kind of plain English breakdown of serious science, ⁓ common sense framing and no one pretending one test is the answer to everything, you'll fit right in with the like minded people in my online community. You can either use the ⁓ QR code up there somewhere or you can use the link in the description if you want to join into live Q &A's every single Sunday, Monday and Wednesday. We have a live Q &A with myself in the room and it's always good fun because there's over 390 members there now so you'll get plenty of chatter about your health and they're all really good very helpful anyway if you enjoyed this video and you've never even heard of ctDNA as a blood test that you could do after you've had some cancer treatment then drop a comment below because I'll be interested in your own story I mean it's much less invasive than say biopsy for instance and you know it's emerging technology that we all need to be aware of I think if you've liked this, please consider sharing and subscribing and if you've got to the end and didn't like it Well, thank you very much. Why not drop a comment on how I could improve things anyway This was just an introduction to a new type of blood test that maybe people haven't heard about and I'm hoping that it will get a lot of interest and more people talking about it Anyway, thanks a lot for watching. See you on the next one