Andrew Brackmann. I'm the diagnostics analyst here at William Blair. This afternoon, we're pleased to have the team from Guardant joining us. We have the co-CEO, AmirAli Talasaz, CFO Mike Bell, and Zarak Khurshid from investor relations. Before jumping into the presentation, just a couple pieces of housekeeping. The breakout for this will be in Jenner A, where we'll be doing open Q&A. For a full list of research disclosures, please visit williamblair.com. So with that out of the way, AmirAli, thanks for joining us.
Okay, great. Thank you very much for having us, and thank you for joining this session. Please note our forward-looking statements. Guardant Health was founded with the mission to give all of us more time, free from this disease. I'm happy that actually I'm standing here with making a great progress toward this journey. We started from advanced cancer management, building portfolio of innovative products, which became standard of care. A big fraction of advanced cancer patients are getting managed with these life-saving and life-impacting products on the therapy selection side. We continued the innovation and execution, and we built the first clinically validated blood-only MRD test called Guardant Reveal. Finally, we delivered on our founding vision by building Shield, the potentially the first FDA-approved Medicare-reimbursed for cancer screening in average-risk patients with the first indication of colon cancer.
I'm very pleased and excited with the recognition by TIME, as they selected Guardant as one of the top 100 most influential companies in 2024. This remarkable product portfolio and excellent commercial execution help us to deliver on the financial track record that you're seeing in this slide. Since our IPOs, we showed CAGR of 40% year-over-year. We've tested more than 550,000 patients so far in terms of clinical tests. Lifetime, we partner with over 170 biopharma partners. I'm excited that starting early this year, in Q1, our core business therapy selection is now cash flow positive for us. And we had a very strong and exciting start in Q1.
We had robust top, top-line growth in Q1, 31% year-over-year growth in terms of total revenue, fueled by 38% year-over-year growth on our precision oncology revenue. This growth has been enabled us to revise our guidance across all the metrics that we had. Starting from revenue side, year-over-year growth revised to be 20%-21% growth. Non-GAAP gross margin, excluding screening, to be 61%-63%. Non-GAAP operating expense have been reduced to $720 million -$730 million, and free cash flow, $60 million -$70 million, reduced year over year to a new target of $275 million -$285 million.
We ended the quarter with $1.1 billion in cash, and we are very focused on driving down the cash burn that we have at Guardant Health, with the goal of getting to a break-even point by 2028 at latest. Now, going into different business areas one by one, and starting with therapy selection. We are the leader in the liquid biopsy market for the therapy selection right now, a market with 700,000 advanced cancer patients, $10 billion TAM opportunity. We launched Guardant360 in 2014, and since then, we have built a comprehensive portfolio of suite of products that helps with the treatment management in advanced cancer patients. Guardant360 CDx and LDT in combination is backed by more than 500 peer-reviewed publications, and the most ordered and clinically validated liquid biopsy for CGP today.
Then we added products around TissueNext. We added product as the only blood-only liquid biopsy to monitor treatment selection for IO and targeted therapies. Interestingly, today, we just announced upgrading this TissueNext product that we have to a broader panel of about 500 gene reportable range. Looking at our testing volume, during the last few years, we had very strong growth on both clinical side, on top, and biopharma side in the bottom, and Guardant360 has been the major contributor in our clinical and biopharma sample testing. Besides volume growth, we had a strong ASP tailwinds this year. Starting from January 1st, the Guardant360 LDT Medicare rate has increased to $5,000.
We had some major wins in terms of commercial coverages last year, that we started seeing some improvement as a result of those coverage policies this year. We are on track to deliver on the long-term ASP targets that we presented at our Investor Day, probably much sooner than what we presented on that day.... which helps to potentially bring forward our timeline to reach company-wide breakeven, sooner than the timeline we talked about before. Talking about our platform technology, smart liquid biopsy. It's first of its kind, kind, and best-in-class technology. Not only this technology can have very high sensitivity in genotyping and finding therapy-related mutation, it can give insight on some clinical information that has not been possible before with just a simple blood test.
I give just a couple examples of what was presented in AACR, and we saw that evidence continued in actually ASCO, that we had just this week and late last week. Some of the notable ones is now with a simple blood test, there are evidence that you can subtype cancers, non-small cell lung cancer versus small cell lung cancer, different subtype of breast cancer you can figure out, transition between these subtypes you can figure out. And also, you can have a general health information across the body. Are you seeing any cardiotoxicity as a result of the drug that the patient is getting? Very early on, a few months earlier than the other mechanism that clinically you can monitor.
For instance, cardiotoxicity in HER2-target therapy is a big issue in managing HER2-mutated cancer patients, and looks like with some early evidence that we have, we can find it with just a simple blood test. We are very pleased with where we are in our therapy selection business, and, there are a bunch of near-term growth drivers all summarized in this slide. So we are very excited about what we could deliver in 2024. Now, moving the gear and talking about MRD and our Guardant Reveal product. We are paving the way for a tissue-free MRD solution. There are 15 million cancer survivors or people with early stage that are eligible for MRD testing. When you look at those, more than 12 million of them have been out of surgery for over five years.
Finding and accessing tissue in these patients who are long after their surgical resection now is a challenge, and just imagine if you can get this MRD information with just a very simple blood test. Our Guardant Reveal is clinically available right now for CRC indication, breast indication, and lung indication. Powered by our smart liquid biopsy platform, now that we added to Reveal actually late last year, now we can look at hundreds to thousands of epigenomics features with a very simple blood test. That helps us to have sensitivity and specificity with very good performances when you compare them with just 16-50 mutations that are getting assayed by tumor-informed assay. With Guardant Reveal, powered by smart liquid Biopsy, now you can track and quantify the tumor fraction with that simple blood test.
This test, as I mentioned earlier, is available for CRC, breast, and lung, and we are gonna add other indications over time. When you look at the MRD field, there are two classes of solution: tissue-free solutions and tissue-informed solution. Tissue-free approach is technically more challenging. It's not the game for everybody to play, but that's typically what we do at Guardant. What looks mission impossible, we figure out innovations to solve it, and now we have this blood-only MRD solution. We believe in long term, the market opportunity would be much higher for tissue-informed assays versus tissue-informed. Why is that? Because of three reasons. Without sacrificing the performance, you can get that information faster, in a matter of days instead of weeks. Second, it's easier. 12 million out of 15 million people are at least five years out of their surgery.
It's logistically challenging to find and get access to those tissue samples. And finally, the third way, and the third reason, is Reveal is in a class of its own. Not only you can figure out the patient is MRD positive or MRD negative, just imagine if you can figure out where the residual disease is. What's the site of what's the subtype of that residual disease? And these are the potential information that we can provide, all powered by smart liquid biopsy platform. We previously talked about the vast size of the biobank that we have accumulated for clinical validation of Reveal across many patient cohorts. We are very pleased with that. That extensive study pipeline not only would help with generating data for reimbursement expansion, but it would help to influence guideline bodies. We are very excited in the field of CRC.
We have data for CRC surveillance that we have presented before that meets all the bars for Medicare coverage expansion. We have submitted that publication for peer review journal, and after submission - after publication, we are planning to submit our Medicare expansion application to MolDX. Looking forward to the end of the year and years to come, we are gonna generate evidence for other cancer types, especially later this year, for breast and other cancer types shortly after as we go to next year.... There are some key near-term inflection opportunity for our Reveal brand. When we are looking about the demand that we are seeing in the marketplace, although we are not growing that volume extensively right now, we are excited by the pool that we are seeing in the market.
We are. As I mentioned, we are making good progress on the CRC surveillance Medicare expansion, which would boost our ASP. We are making very good progress on reducing the COGS of Reveal, which in combination, these two would make a gross margin negative test Reveal in 2024, to a gross margin positive test as we go to next year, pending expansion of our CRC Medicare reimbursement to cover the surveillance cases, and then we can really drive the volume growth for Reveal. We believe over time, we can get to a 60% gross margin for Reveal. Now, talking about screening, a test that can revolutionize cancer screening in 120 million average-risk patient population. We are pioneering a new category of blood-based cancer screening.
When we look at cancer as a whole, when you just look at the 26 different cancers, the survival, five-year long-term survival, is just 14% when those cancers are diagnosed at late stage. Same cancers, comprising 87% of all cancers in U.S., if you diagnose them at early stage, localized or regional, you get a huge improvement in survival, bumping to 65%-90%. So why we are not there for cancer screening of finding these cancers earlier? First, you need to have a solution that can detect cancers at early stage with good performance. Second, you need to make sure people get access to that test in terms of reimbursement and accessibility, equitable access, access to that innovation. And lastly, you need a modality that patient, in fact, complete the test with a pleasant customer experience.
The good thing about blood, you can get all the above. We started with CRC as our lead indication to open up the pathway for accessible blood-based cancer screening, as there are reimbursement pathways and regulatory pathways for CRC indication, and we are very pleased with publication of our pivotal ECLIPSE study earlier this year in New England Journal of Medicine. This publication is a endorsement of the clinical data and the study quality that we've shown, and we were pleased with the level of attention that we got from media, consumers, KOLs, stakeholders, after this publication came out about the potential of this test in revolutionizing what we are doing in the field of cancer screening right now.
To put this in context, in terms of the performance that we've seen with our Shield assay for CRC screening, in this slide, I'm showing the sensitivity of Shield and specificity of Shield relative to other non-invasive tests, all recommended by guidelines: stool test, mt-sDNA, FIT, and high-sensitivity FOBT. What you are seeing in this slide, we have a sensitivity, specificity in range for blood test relative to other guideline-recommended stool-based test for the first time ever. This performance meets the bar for FDA approval and Medicare reimbursement for Shield in average-risk patient population. Also, we've done some randomized studies. The right one is with the Shield, and the left one is with another blood test.
Randomized studies that have shown what you could do with usual care, colorectal cancer screening, utilizing just colonoscopy and stool-based test, and then with an interventional arm, when you're giving access to colonoscopy, stool-based test, and a blood test. What we've seen is a huge increase in the overall screening rate. Like of note, on the right, in a study with Kaiser Permanente, a randomized study of 2,000 patients, we've seen a 2.4x increase in Kaiser when Shield is getting incorporated into practice, on top of FIT, mt-sDNA, and colonoscopy. Earlier. Not this month, actually late last month, on May 23rd, we had FDA advisory committee panel for Shield as part of the review process of our PMA package for Shield, and we are very excited that that panel strongly recommended approval of this test as a primary non-invasive screening option.
You see the proposed indication use and indication for use here, that Shield is intended for colorectal cancer detection and cancer screening in average-risk patient population, and voting was strong in terms of safety, efficacy, and the benefit outweighing the risk in the proposed intended use. CMS, back in January 2021, had wrote a national coverage determination for blood-based colorectal cancer screening test. That a blood test is covered for every three-year testing, as long as it's FDA-approved for cancer screening indication, with sensitivity and specificity of 74% and 90%, respectively. As a result, as long as we get FDA approval, we are gonna be the first FDA-approved Medicare-covered blood test for colorectal cancer screening, with interval testing of every three years based on this NCD.
Now, there are questions in the field: could a blood test really bring the unscreened patient population around the table of screening? I showed some randomized studies in Kaiser, for instance, but let's maybe look at some other information. Out of 120 million people, as I talked earlier, 50 million people are unscreened. 75% of cancer-related death is coming from the people who are not up-to-date with their colorectal cancer screening. Blood is very well positioned to open up this significant unmet need and market opportunity. When you look at national health surveys, patients aged 50 years and above, 87% of them have seen their doctor during the last 12 months, out of which, in fact, 91% of them have done a blood work during the last 12 months.
When you just look at our experience with Shield LDT during the last two years, what we continue to see is a strong completion rate or adherence rate, that when a doctor enthusiastically orders Shield, in fact, patients complete that test. As we are getting to get ready for Shield IVD commercial launch, post-expected FDA approval, we are very excited about our upcoming catalyst that we are going to have for Shield in near future. We just had a very successful advisory panel. We're expecting this FDA approval in 2024, and right after, Medicare coverage is going to get activated based on the NCD. We are going to launch the IVD product this year.
As we go to next year, we are expecting to get advanced diagnostic laboratory test status with improved Medicare pricing as a result of it, and also be included in American Cancer Society next year. As I mentioned, our pathway is toward building a blood test for multi-cancer detection and screening. We started with CRC strategically to make sure we are building an accessible blood test for cancer screening, and then we are adding other indications to the same test, starting from lung cancer, and soon after, we would add a panel of multi-cancers to the same Shield blood test with just a different algorithm to look at early signs of early cancer stage with same Shield test. Now, in summary, when we look at the whole Guardant Health story, I'm very proud of where we are, but this is just the beginning of Guardant Health.
When we are looking at the therapy selection, there are a lot of growth drivers and catalysts in front of us, with very strong pipeline activities around MRD and screening. We are very excited about what we can do in future by offering more time to all of us, and bringing a better future for everybody. Thank you for your attention, and I think we take the Q&A somewhere else.