The journey for an oncology patient often involves a relentless cycle of clinic visits, treatments, and crucially to the work I am involved with, blood draws for diagnosis, monitoring and MRD. This routine, while essential, presents significant burdens – from travel and time off work to the physical discomfort and anxiety associated with frequent venipuncture. But novel methods may enable blood collection the comfort and convenience of home.

This vision is rapidly moving from concept to reality, driven by advancements in both molecular diagnostics and, critically, revolutionary methods of blood collection. The promise lies in enabling cancer monitoring to be more accessible, less intrusive, and seamlessly integrated into a patient’s life.

PS: This post was inspired by Brad Evans (Merck) and Jordan Feeny (Natera)’s recent poster at ASCO’25: Feasibility of ctDNA detection with a low-volume blood collection device – using Tasso+. And it follows on from a blog post about longitudinal monitoring of ctDNA from blood spots, but I’ve dug a little deeper into what’s out there today even if there’s not a ton of ctDNA data yet!

The Power of Molecular Assays: A Quick Look

For many of my readers, the significance of molecular assays that use circulating tumor DNA (ctDNA) detection is well understood. These powerful tools offer non-invasive insights into a patient’s cancer, enabling molecular diagnostics, minimal residual disease (MRD) detection and treatment response monitoring for early recurrence detection. Currently, high-sensitivity ctDNA assays typically rely on larger volume venous blood draws, usually one or two 10-20 mL tubes of whole blood that are double-spun, to ensure sufficient material for detecting these often scarce biomarkers. The challenge, then, is to achieve this same level of precision with significantly smaller, patient-friendly samples.

Emerging At-Home Blood Collection Methods: A Revolution in Miniaturization

The true game-changer for at-home oncology testing lies in a new generation of blood collection devices designed for patient self-collection with minimal training. These innovations are reshaping how we think about obtaining diagnostic samples:

1. Capillary Blood & User-Friendly Microcollection:

While traditional microcollection tubes have been around for a while, newer systems are specifically engineered for ease of home use, collecting capillary blood (typically from a finger or forearm stick) with improved accuracy and patient comfort.

• BD MiniDraw™ Capillary Blood Collection System: Designed with simplicity in mind, this system aims to make capillary blood collection straightforward for patients, yielding approximately 1 mL of whole blood.
• RedDrop One: This device offers a unique approach to self-collection of capillary blood from the forearm, emphasizing ease and consistency for diagnostic purposes, with volumes typically ranging from 10 to 50 µL.

2. Volumetric Microsampling: Precision in Tiny Drops:

Perhaps the most exciting frontier for oncology monitoring, these devices collect extremely precise, small volumes of blood, often then dried onto a substrate for stable transport. This combination of minimal invasiveness and volumetric accuracy is key.

• TASSO Devices (TASSO+, TASSO-SST, TASSO-M20): Tasso’s range of devices allows for patient self-collection of whole blood, serum, or micro-samples from the upper arm. The TASSO+ can collect 200-600 µL of whole capillary blood, TASSO-SST collects 150-500 µL of serum, and the TASSO-M20 provides four precise ~17.5 µL micro-samples. Their “push-button” activation simplifies the process, making it highly amenable to remote use.
• Mitra® Devices (Neoteryx): Utilizing Volumetric Absorptive Microsampling (VAMS) technology, Mitra devices precisely collect a fixed volume of blood (typically 10-30 µL per tip) from a fingerstick. This volumetric precision is crucial for quantitative analyses, and the dried format aids stability during shipping.
• hemaPEN® (Trajan Scientific and Medical): This innovative device enables the collection of four exact 10 µL dried blood samples. Its multi-sample capability from a single fingerstick is valuable for repeat testing or multi-analyte assays.
• Capitainer® B 50: Capitainer devices are designed for highly accurate, fixed-volume dried blood spot collection (50 µL) from a fingerstick. They ensure that the exact volume of blood is absorbed, addressing a common variability challenge with traditional DBS cards.
• Timepoint LCM: An at-home device for for collection and stable recovery of ctDNA from upper arm capillary blood (500 ul)

Prominent Blood Collection Methods and Devices

The “Ifs” and “Buts”: Overcoming Challenges for Oncology

While the collection technology is advancing rapidly, significant hurdles remain, particularly when considering highly sensitive molecular oncology assays:

• The Volume Challenge: Current high-sensitivity ctDNA assays are often optimized for larger plasma volumes derived from 10-20 mL of whole blood. These micro-collection methods yield blood volumes in the microliter range. The critical question is whether molecular oncology assays can be re-optimized or new ones developed that maintain the same diagnostic sensitivity and specificity with significantly smaller input volumes. This is an intense area of ongoing research.
• The “Low Levels” Challenge: ctDNA is often present at extremely low concentrations, especially in the MRD setting or in early-stage cancers. The sensitivity of a molecular assay is directly linked to the amount of input material. Achieving the same robust limit of detection (LOD) and quantification (LOQ) with lower input volumes would be great but may be impossible. While recent data, from Personalis e.g. ESMO 2024 TRACERx NeXT Personal from Charlie Swanton, or Natera e.g. their ASCO 2025 presentations on the Signatera Genome assay, or Foresight Diagnostics e.g. their ASCO 2025 data on PhasED-Seq in DLBCL, demonstrates phenomenal sensitivity in detecting ctDNA across various cancer types, it’s vital to note that these studies typically leverage standard, higher-volume venous blood draws. Future work must validate if this same level of clinical sensitivity can be achieved using micro-samples from home-based collection devices, or if those highly-sensitive tests can still be useful if constrained by blood volume.
• Sample Quality and Stability: Ensuring the integrity and stability of delicate biomarkers like ctDNA during transit from a patient’s home to the lab, especially when collected in a dried format, is another key consideration. Appropriate preservatives and storage conditions are essential.
• Regulatory and Clinical Validation: Rigorous clinical validation studies demonstrating the equivalence or superiority of these at-home methods to traditional venipuncture are indispensable for widespread adoption and regulatory approval in oncology.

The Transformative Potential: Why It Matters

Despite these challenges, the potential impact of at-home blood collection in oncology is immense:

• Patient Empowerment: Granting patients greater control and comfort in their care journey.
• Increased Access: Breaking down geographical and mobility barriers, ensuring patients in rural areas or with limited mobility can still receive cutting-edge monitoring.
• More Frequent Monitoring: Easier access could enable more frequent testing, potentially allowing for earlier detection of disease changes or recurrence, leading to timelier intervention.
• Enabling Decentralized Clinical Trials: A cornerstone for modern cancer research, allowing broader patient participation regardless of location.

Conclusion: The Road Ahead

The convergence of innovative, low-volume blood collection technologies and increasingly sophisticated molecular assays promises a new era for oncology diagnostics. While the scientific community is actively working to overcome the technical challenges related to sample volume and ultra-low ctDNA levels, the advancements are undeniable – and I’d call out the Priming Agents work published last year (see my blog) and being spun out by Amplifyer.bio. As such, I believe the vision of oncology patients confidently managing parts of their care from home, leading to earlier insights and more personalized treatment paths, is not just a dream – it’s becoming a tangible goal, set to redefine the patient experience in cancer care.