What Is Precision Oncology and How It's Changing Cancer Treatment

Precision oncology is cancer treatment guided by the specific molecular biology of a patient's tumor, not simply where in the body that tumor originated. Instead of asking "what is the standard protocol for this cancer type?", precision oncology asks: "what is driving this particular tumor's growth, and what does its biology suggest about how to treat it?"

The distinction matters enormously. Tumors that carry the same name can behave in completely different ways depending on their underlying biology. Two patients with identical diagnoses may have cancers driven by different mutations, expressing different proteins, and responding to entirely different drugs. Precision oncology is the framework built around recognizing and acting on that difference.

For patients, it represents a shift from being treated as a category to being treated as an individual, reshaping how oncologists think, how clinical trials are designed, and what questions patients can meaningfully ask about their care.

The Old Model: Location-Based Treatment

For most of modern oncology's history, treatment was organized around anatomy. A tumor in the lung was lung cancer; a tumor in the colon was colon cancer. Once the location was confirmed and the stage established, treatment followed a defined protocol (surgery, radiation, chemotherapy, or some combination), largely standardized across patients with the same diagnosis.

This model had real strengths: it was systematic, reproducible, and grounded in large clinical trials. For many patients, standard protocols remain an effective starting point.

But the location-based model treats all tumors in the same organ as fundamentally similar, when they often are not. Two patients with pancreatic cancer may have completely different molecular profiles. Two patients with melanoma may carry mutations that respond to opposite therapeutic strategies. Treating them identically because their tumors share an anatomical address ignores information that could be clinically meaningful. The location-based model was not wrong. It was incomplete. It was the best available when the tools to look deeper did not exist. Those tools now exist.

The New Model: Biology-Based Treatment

Biology-based treatment starts with characterizing the tumor itself (its mutations, its gene expression patterns, the proteins it produces, the signaling pathways it depends on) and using that information to guide therapeutic decisions.

Several categories of biological information have become central to this approach.

Mutations are changes in the DNA sequence of tumor cells. Some mutations activate growth pathways, and drugs exist that specifically inhibit those pathways. A patient whose tumor carries an EGFR mutation, for example, may be a candidate for therapies that target that specific pathway, therapies that would not be relevant to a patient whose tumor lacks that mutation, even if both patients have the same type of cancer.

Biomarkers are biological indicators (proteins, genes, or other molecular signals) that can predict how a cancer is likely to behave or respond. PD-L1 expression and tumor mutational burden are examples used to inform immunotherapy decisions. These markers vary between patients even when the diagnosis is identical.

Gene expression profiles reveal which genes are active in tumor cells and at what intensity. Two tumors of the same named type may have dramatically different expression patterns. Breast cancer, for example, is now understood to encompass multiple molecularly distinct subtypes with different treatment implications. The same diagnosis can legitimately lead to very different treatment paths depending on what the biology reveals.

What Powers Precision Oncology

Precision oncology runs on a set of analytical tools that were either unavailable or prohibitively expensive a decade ago. Each requires tumor tissue, and the quality and type of tissue determines what analysis is possible.

Genomic sequencing reads the DNA of tumor cells to identify mutations and other variants that may be actionable, meaning there is a drug or clinical trial that targets them. Sequencing panels can analyze dozens of clinically relevant genes simultaneously; comprehensive genomic profiling examines the entire tumor genome.

Immunohistochemistry (IHC) uses antibodies to detect specific proteins in tumor tissue sections, revealing whether particular receptors or markers are present and at what levels. It remains one of the most widely used precision tools in clinical practice.

Functional assays expose living tumor cells directly to drugs and measure how those cells respond. Rather than inferring sensitivity from genetic data alone, functional assays observe it directly, though they require viable, living cells preserved within a narrow window around surgery.

Organoids are miniature, three-dimensional tumor models grown from a patient's own living cells. They preserve the structural complexity of the original tumor, making them more predictive than simpler cell culture systems. Like functional assays, organoids cannot be built retroactively from tissue that was not preserved at surgery.

All of these tools depend on tissue. No tissue means no analysis.

Why Tissue Matters for Precision Oncology

Precision oncology is only as precise as the tissue it is built on. Without adequate tumor tissue, properly collected and properly preserved, none of the analytical tools described above can be applied. This is the constraint that patients often do not learn until after surgery, when the opportunity to act on it has passed.

Not all preserved tissue is equivalent. Formalin-fixed, paraffin-embedded (FFPE) tissue, the standard hospital pathology format, supports some genomic analyses and immunohistochemistry, but cannot support applications that require living cells. Organoid models and functional drug assays require cryopreserved, viable tissue collected at surgery and processed immediately. That material cannot be obtained retroactively.

Quantity matters too. A standard diagnostic biopsy may confirm a diagnosis but fall short of what is needed for comprehensive genomic profiling, functional assays, and organoid culture simultaneously. Once a tumor is removed and tissue discarded or fixed in a way that kills the cells, the opportunity for living-cell analysis is gone.

What It Means for Patients

For a patient navigating a cancer diagnosis, precision oncology means there may be more options available than a standard treatment protocol reflects, but accessing those options requires information that standard protocols do not automatically generate, and tissue that standard pathology workflows do not automatically preserve.

Some of those choices must be made before surgery. Thinking about tissue preservation before the initial procedure is the only way to keep living-cell analysis available as an option. Once the tumor is removed and the tissue discarded, that door closes.

Asking your surgeon and oncologist what molecular analysis will be performed, what tissue will be retained, and what additional preservation options exist is increasingly part of informed cancer care. Precision oncology is not a guarantee of any particular outcome. It is a framework for making decisions based on more information. Having access to that information starts with having access to the tissue.

Kernis Health provides concierge coordination and tissue preservation services. This article is informational, not medical advice. Decisions about your care should be made with your oncology team.