Episode Overview

Title: This Startup Wants To Catch Cancer Before It Spreads
Podcast: Y Combinator Startup Podcast
Date: April 6, 2026

Main Theme:
This episode delves into Billion to One — a molecular diagnostics company that started with the radical goal of detecting tiny traces of disease in blood. The founders, Ozan and David, share how their innovations in prenatal genetic screening are expanding to tackle the “holy grail” of medicine: detecting cancer early, even before Stage 1. The episode covers their technical breakthroughs, scrappy origins, commercialization journey, culture, and ambitious next steps.

Key Discussion Points and Insights

1. The Needle in a Haystack Problem in Genetic Testing

• Challenge:
  Detecting diseases caused by minuscule changes—a single base pair among 3 billion in the human genome.

  • “There are 3 billion base pairs in the human genome. ... It's usually only one base pair that's different. So you're looking for one base pair that's different out of billions. And that's where the Going To One name came from.”
    — David [00:12]

• Initial Product:
  The Billion to One prenatal test identifies genetic disorders in fetuses non-invasively, with wide adoption in the US.

2. Breakthrough Technology: How They Find the Needle

• Key Insight:
  Both fetal DNA and tumor DNA in blood are extremely rare, so conventional tests get overwhelmed by background noise.

  • “[DNA] is very dilute and rare… every molecular diagnostics approach requires …amplify this DNA billions of fold. The problem is that this DNA amplification process can add tremendous noise... So what we have done is to add a synthetic DNA into the patient sample that we get before any amplification happens.... we can remove those errors from the sequencing data.”
    — Ozan [03:16]

• Billion to One’s Solution:

  • Add known synthetic DNA molecules before amplification.
  • Track and subtract amplification-induced noise using machine learning.
  • Makes a previously intractable biology problem into a solvable math problem.

• Result:
  They can now detect ultra-rare DNA signatures in blood, enabling detection of both genetic disease and cancer that was previously invisible.

3. From Scrappy Origins to Multi-Billion Dollar Scale

• Early Days:
  Started with half a lab bench, sharing supplies. First fundraising of $300K took six months; traction was hard to build.

  • “It was a struggle even to get very common kind of chemical suppliers to allow us to buy things from them... The first fundraising… was one of the most difficult things I have done.”
    — Ozan [07:17, 07:43]

• Solving the Sales Challenge:
  After launch, adoption was slow—only one physician using the test two months in.

  • “I told our VP of sales, I was like, look, in five months you hired only one rep. Obviously that is not working. I need you to hire in the next three weeks, five additional sales reps...”
    — Ozan [08:31]
  • Pivoted to direct patient outreach, empowering patients to ask doctors for the test, leading to much-needed traction.

• Scale Today:

  • Processing 600,000 tests per year, ~20% US market share in prenatal screening.
  • Went public with a valuation over $4B in the past year.

4. Lab Tour: Advanced Automation, AI, and Barcoding

• Lab Process:

  • Samples tracked by AI-driven information management.

  • Use of computer vision for sample tracking and "Accessioning in 60 Seconds" to accelerate throughput.

  • Liquid handling robots and proprietary reagents ensure accuracy and minimize bias.

  • Massive multiplexing: thousands of samples barcoded then pooled, followed by computational demultiplexing.

  • “When you look at the data, every time you see that barcode, you know that that sequence belongs to this patient.”
    — Ozan [12:07]

  • Can expand to 2 million tests/year in current facility; one in three US babies could be tested with their technology.

• Result Interpretation:
  Labor-intensive cases (about 20 people on some complicated samples); standard cases auto-analyzed.

5. Strategic Expansion: From Prenatal to Cancer

• Product Roadmap:

  • Step 1: Prenatal genetics (solved)
  • Step 2: Late-stage cancer MRD (Minimal Residual Disease) test (recently commercialized)
  • Step 3: Early-stage cancer detection and annual universal cancer screening (R&D in progress)
  • Potential Step 4: True, population-scale preventative screening.

• Strategic Choice:
  Started with prenatal genetics—a less capital-intensive, more winnable market—then reinvested in oncology R&D.

  • “It is very important to actually select the right problem, the right minimal viable product to work on. Because if we started... on the oncology side, it would have been far more difficult to achieve that initial, successful commercialization.”
    — Ozan [13:30]

6. Real Impact: A Patient Story

• “...this was a fairly young, in their 40s, individual with metastatic colorectal cancer... about to go into hospice... We ended up testing this person... and identified that this person was eligible for a therapy called immunotherapy, based on identifying microsatellite instability in the tumor DNA... this person went on to immunotherapy and did really remarkably well. Sometimes doctors describe the patient response as the cancer melting away.”
  — David [14:12]

7. Team Culture and Structure

• Unique Hiring Philosophy:
  Seeks not just an interdisciplinary team but interdisciplinary individuals (scientists who can code, analyze data, and understand lab chemistry).

  • “We say we're not looking to an interdisciplinary team here. We're actually looking for interdisciplinary people.”
    — David [15:32]

• Startup-Within-a-Startup:

  • Each product owned end-to-end by a small, dedicated group reporting directly to founders.
  • Avoid bureaucracy, fast iteration cycles, high autonomy.
  • “It almost creates this interesting structure where we have many startups within the larger company. Each one owns a product and makes it better and better.”
    — Ozan [16:15]

8. The Vision: Universal, Early Cancer Detection

• Ultimate Goal:
  Detecting cancer before it ever becomes visible on scans—catching it at its truly earliest, most treatable stage.

  • “If we can screen everyone once a year and be able to conclusively say that this small group of people have early stage cancer, that would be amazing because those tumors can often be removed before it spreads.”
    — Ozan [17:58]

• Why No One Did This Before:

  • Most attempts aimed too big, too early—required huge capital and long timelines.
  • Founders’ discipline and resource constraints necessitated a stepwise, profitable approach.
  • “Being resource limited is sometimes very helpful, right? If you wanted to solve early detection from the very beginning... you would have to raise more than a billion dollars without generating a single dollar of revenue.”
    — Ozan [19:02]

• Founders’ Ethos:

  • “Pressure is a privilege. ... Trying to change healthcare while also growing this fast, you know, while being profitable, is even more difficult. ... You are going to be extremely proud of what you are going to achieve here.”
    — Ozan [19:48]

Memorable Quotes

• “We have a saying that pressure is a privilege.” — Ozan [19:48]
• “Everyone wants to make an impact, but you have to do it step by step. ... The great thing about our technology is that it does allow us to have this step-by-step approach to being able to get to a place where we can solve a problem for millions of cancer patients.” — Ozan [19:15]
• “We're not looking for an interdisciplinary team here. We're actually looking for interdisciplinary people.” — David [15:32]
• “Sometimes doctors describe the patient response as the cancer melting away.” — David [14:25]
• “I would be very proud of what we achieve even if we just solved the biggest prenatal problems. But the great thing about our technology is that it does allow us to have this step by step approach...” — Ozan [19:12]

Timestamps for Notable Segments

• 01:44 — What Billion to One does and why cell-free DNA in blood matters
• 03:16 — Ozan explains their unique synthetic DNA approach
• 07:43 — Struggles with early fundraising and adoption
• 08:31 — Rethinking sales strategy for traction
• 10:23 — Implementing AI and automation in their lab
• 12:07 — How samples are barcoded and demultiplexed
• 13:30 — The business and technical reasoning for starting in prenatal
• 14:12 — Real-world cancer patient case study
• 15:32 — Their philosophy on hiring and research structure
• 17:38 — Vision for detecting microscopic and pre-stage-1 cancer
• 19:02 — Why their stepwise approach works and “pressure is a privilege”

Conclusion

Billion to One’s story is a modern startup epic: combining deep science, clever engineering, startup hustle, and smart go-to-market tactics to solve the world’s hardest medical detection challenges. Starting with prenatal testing, scaling to cancer monitoring, and now aiming for universal early cancer screening, their work is transforming what’s possible in diagnostics — and saving lives in the process. The founders’ blend of scientific rigor and entrepreneurial resourcefulness stands out as a new benchmark for mission-driven healthtech.