Revolutionary advancements in medical technologies have armed physicians with state-of-the-art methods for detecting and monitoring cancer. Two of these methods are liquid and solid biopsies which provide physicians and researchers with integral information about a patient’s condition.
What is a Solid Biopsy?
Solid biopsies are the traditional method of analyzing tumors; this typically involves extracting samples of tissue from the tumor using a needle or scalpel1. Microscopy is then used to examine the samples, along with molecular analysis and genetic profiling. This method is instrumental in diagnosing different types of cancers and determining what stage of disease the patient is in. Solid Biopsy is typically performed when there is a palpable mass present or when a specific region requires more in-depth examination1.
This method of sampling is advantageous for several reasons. Direct tissue sampling allows for detailed analysis of the tissue architecture of the mass, as well as morphology and interactions of cells. The tissue collected with solid biopsy provides sufficient genetic material for comprehensive genetic and molecular profiling1.
One limitation of this sampling method is its invasiveness; puncturing of the skin with a sharp such as a needle or scalpel will always carry the risk of infection. This injury to the skin can be physically uncomfortable for the patient while also being aesthetically displeasing, as solid biopsies are known to leave scars. Tumor heterogeneity can also present an obstacle for solid biopsy by not providing a full picture of the characteristics of the sampled mass.
What is a Liquid Biopsy?
Liquid biopsies are a typically minimally invasive collection method that samples fluid from the body in a myriad of ways including intravenous blood draws, urine collection, and saliva swabbed from the mouth2. These liquid samples are then molecularly analyzed to measure extracellular nucleic acids that are circulating such as cell-free DNA (cfDNA), circulating tumor DNA (ctDNA), and circulating tumor cells (CTCs)2. cfDNA and ctDNA can be isolated from blood samples and are two of the most important nucleic acids in regard to cancer research and treatment2. The liquid sample collected from the biopsy, along with the genetic material contained within it, is analyzed for biomarkers released from the tumor.
While liquid biopsy is typically regarded as minimally invasive and relatively painless compared to solid biopsy, not every liquid biopsy is minimally invasive; collection of cerebrospinal fluid is one method of liquid biopsy performed with a spinal tap which can be painful for the patient. Liquid biopsy does not provide as much specific information about the tumor as solid tissue collection.
How are Liquid and Solid Biopsies Used to Detect Cancer?
Histopathological assessment with solid biopsies aids diagnosis and prognosis of cancer by allowing physicians to analyze tumor cell differentiation, invasion, and metastasis directly. Tissue biopsies are fully utilized when a known tumor’s location is confirmed and available for extraction. The information provided from direct tissue sampling is integral for identifying the type of cancer present, its genetic makeup, and any mutations to the genome, including those that may make the tumor treatment-resistant3.
Liquid biopsies are best used for screening, identifying mutations in metastatic cancer, and tracking mutations for treatment4. Whole genome sequencing from cfDNA can be used to map the entire tumor’s genome and characterize any alterations to the genome or mutations. Another advantage of this biopsy method is that it is able to collect information about tumors that may have metastasized or are present in regions of the body that are not able to be collected via solid biopsy.
Conclusions
Both solid and liquid biopsies offer unique advantages and disadvantages depending on a patient’s prognosis. Omega Bio-tek offers nucleic acid purification kits that fit the needs of the researcher no matter which biopsy method is used. For solid biopsy samples, Omega Bio-tek offers the E.Z.N.A.® FFPE DNA Kit and the E.Z.N.A. FFPE RNA Kit, which are column-based solutions, and the Mag-Bind® FFPE DNA/RNA 96 Kit which can be used by the researcher to isolate both DNA and RNA from the same FFPE sample. For liquid biopsy samples, the Mag-Bind cfDNA kit can target the isolation of small fragments of cfDNA.
For more information or to request a sample of these kits, visit our product pages:
Mag-Bind® FFPE DNA/RNA 96 Kit
Mag-Bind® cfDNA Kit
References
- Russano, M., Napolitano, A., Ribelli, G. et al. (2020). Liquid biopsy and tumor heterogeneity in metastatic solid tumors: the potentiality of blood samples. J Exp Clin Cancer Res 39, 95 https://doi.org/10.1186/s13046-020-01601-2
- Nikanjam, M., Kato, S., & Kurzrock, R. (2022). Liquid biopsy: current technology and clinical applications. Journal of hematology & oncology, 15(1), 131. https://doi.org/10.1186/s13045-022-01351-y
- Lin, L.H., Allison, D.H.R., Feng, Y. et al. (2021). Comparison of solid tissue sequencing and liquid biopsy accuracy in identification of clinically relevant gene mutations and rearrangements in lung adenocarcinomas. Mod Pathol 34, 2168–2174 https://doi.org/10.1038/s41379-021-00880-0
- Zhang, S. (2016). One Patient, Two Cancer DNA Tests, Two Different Results. The Atlantic.
