The Genetics of Cancer: How Tumours Hijack DNA — and How Science Is Fighting Back

In February 2026, researchers at the Spanish National Cancer Research Centre published a finding that changed how scientists understand one of the most destructive events in tumour development. They identified the enzyme responsible for chromothripsis — a catastrophic process in which an entire chromosome is shattered into dozens or hundreds of fragments, then randomly reassembled in the wrong order. The enzyme is called N4BP2, and it is present in approximately one in four human cancers.

Chromothripsis had been known about since 2011, but for fifteen years nobody knew what caused it. Now they do. And understanding the cause means understanding, for the first time, a molecular mechanism that drives roughly 25 percent of all human cancer cases — affecting hundreds of millions of people worldwide.

Cancer is not a single disease. It is a vast collection of diseases — over 100 distinct types — united by one fundamental characteristic: cells that have lost the genetic controls that regulate their growth and division, and that now multiply without limit, invade surrounding tissue, and spread to distant organs. At its core, cancer is a disease of DNA. Every case begins with a genetic error — a mutation, a deletion, an amplification, a rearrangement — that disrupts the molecular machinery keeping cell division under precise control.

Understanding that machinery — how it works, how it breaks, and how it can be repaired or targeted — is one of the defining missions of modern genetics research. In 2026, that understanding is advancing faster than at any previous point in history.

What Happens to DNA When Cancer Develops

Every cell in your body divides according to a tightly regulated programme. When a cell divides, it copies its entire genome — approximately three billion base pairs of DNA — and distributes one complete copy to each daughter cell. This process is not perfectly accurate. According to research published in leading journals, the human genome accumulates an average of one to two new mutations per cell division simply through the natural imprecision of DNA replication.

Most of these mutations are harmless. They occur in regions of the genome that do not affect cell function, or they are corrected by the cell’s DNA repair machinery before they can cause damage. A small fraction, however, occur in genes that regulate cell growth — and when they do, they can tip the balance between controlled proliferation and cancer.

Researchers distinguish between two broad categories of cancer-relevant genes. Oncogenes are genes that, when mutated, actively drive cell growth — like a stuck accelerator. Tumour suppressor genes are genes that normally restrain cell division — like a brake. Cancer typically involves both: oncogenes that have been switched on inappropriately, and tumour suppressors that have been inactivated.

According to the precision oncology database compiled by SmartCancer in 2026, cancer development is not random — it follows an evolutionary process in which mutations that provide survival advantages are selected over time, building on each other through successive cell generations. A single mutation is rarely sufficient to cause cancer. Most tumours require the accumulation of multiple genetic alterations, typically over years or decades, before the cell acquires all the properties that make it fully malignant.

The Hallmarks of Cancer: Updated for 2026

In 2000, two researchers — Douglas Hanahan and Robert Weinberg — published one of the most influential papers in the history of cancer biology, describing what they called the hallmarks of cancer: a set of acquired capabilities that distinguish cancer cells from normal cells. The original list included six hallmarks. It has been revised twice since, and as of 2026, the framework maintained by the Jackson Laboratory identifies an expanded set of capabilities that cancer cells must acquire to become fully malignant.

These capabilities include sustained growth signalling — cancer cells generate their own growth signals rather than depending on external ones. They resist the cellular mechanisms that would normally suppress excessive growth. They evade programmed cell death. They enable replicative immortality — largely by reactivating telomerase, the enzyme that maintains telomere length, as discussed in our article on telomeres and aging. They stimulate the formation of new blood vessels to supply the growing tumour. And they invade surrounding tissue and spread through the bloodstream to distant organs — the process of metastasis that makes cancer so dangerous.

According to the Jackson Laboratory’s 2026 analysis, the most recent additions to the hallmarks framework include epigenetic reprogramming — cancer’s ability to silence tumour suppressor genes through epigenetic modifications — and phenotypic plasticity, the ability of cancer cells to switch between different cell states, making them harder to target with treatment.

Oncogenes: The Molecular Accelerators

Among the most studied oncogenes are the RAS family — KRAS, HRAS, and NRAS — which encode proteins that act as molecular switches in cell signalling, toggling between active and inactive states to control cell growth. When these genes are mutated, the switch becomes permanently stuck in the on position, continuously driving cell division regardless of external signals.

According to research from the Jackson Laboratory published in March 2026, KRAS mutations are among the most common drivers of cancer across multiple tumour types, including colorectal cancer, lung cancer, and pancreatic cancer. KRAS was considered undruggable for decades — the protein structure offered no obvious site where a drug molecule could bind and block it. The development of KRAS G12C inhibitors in recent years marked a breakthrough, and 2026 research is focused on overcoming the drug resistance that eventually develops in most patients treated with these agents.

HER2 is another oncogene of major clinical significance. Gene amplification — in which a section of DNA is duplicated many times — can cause HER2 to be massively overexpressed, driving aggressive tumour growth. HER2-targeted therapies have transformed the treatment of HER2-positive breast cancer, and genomic testing for HER2 amplification is now standard clinical practice.

Pancreatic Cancer and the GATA6 Discovery

In March 2026, scientists published a finding with significant implications for one of the deadliest cancers. Pancreatic cancer kills approximately 90 percent of patients within five years of diagnosis — largely because it is usually detected late, and because most tumours rapidly develop resistance to the available chemotherapy drugs.

According to ScienceDaily’s report on the research, scientists identified a gene called GATA6 as a crucial molecular switch determining whether pancreatic cancer cells resist chemotherapy or respond to it. GATA6 keeps tumours in a more differentiated state — closer to normal pancreatic tissue — which makes them more sensitive to treatment. When GATA6 is inactive, tumours shift to a more primitive, stem-cell-like state that is profoundly chemotherapy-resistant.

The finding opens a therapeutic strategy that had not previously been considered: rather than simply attacking cancer cells directly, drugs that restore GATA6 activity could shift resistant tumours back into a treatable state. Studies are now underway to identify compounds capable of doing this. For a cancer that has seen minimal improvement in survival rates for decades, the identification of a molecular switch controlling treatment resistance is a significant step.

A Hidden Layer of Cancer: RNA and Epigenetics

In February 2026, a study published through ScienceDaily described a discovery that revealed an entirely new dimension of cancer biology. Researchers investigating breast cancer identified a mysterious class of RNA molecules — not previously characterised — that turned out to form unique molecular signatures across dozens of tumour types. These molecules form part of what researchers call a hidden layer of the cancer genome, invisible to standard DNA sequencing.

The discovery matters because it suggests that cancer’s genetic complexity is even greater than current models account for. Cancer genomics has, until recently, focused primarily on DNA mutations. The emerging science of the cancer epitranscriptome — the chemical modifications on RNA — is revealing that cancer also hijacks RNA-level regulation in ways that create new targets for therapy and new biomarkers for diagnosis.

Cancer’s relationship with epigenetics is also central to its biology, as explored in our detailed article on epigenetics and gene expression. According to the Van Andel Institute, which is a world leader in cancer epigenetics research, cancers often have multiple epigenetic errors that reinforce each other — keeping tumour suppressor genes permanently silenced while allowing pro-cancer genes to remain active. These epigenetic errors offer important opportunities for treatment: unlike DNA mutations, they are potentially reversible, and several epigenetic drugs have already received regulatory approval for specific cancer types.

Chromothripsis: When Chromosomes Shatter

The February 2026 identification of N4BP2 as the enzyme behind chromothripsis represents one of the most mechanistically important cancer genetics discoveries of recent years. Chromothripsis — from the Greek words for chromosome and shattering — is a process in which a chromosome undergoes catastrophic fragmentation during cell division, producing dozens or hundreds of pieces that are then randomly ligated back together in the wrong order.

The genomic rearrangements produced by chromothripsis can simultaneously inactivate multiple tumour suppressor genes and amplify multiple oncogenes in a single catastrophic event — compressing into one cell division what would otherwise take years of gradual mutation accumulation. According to research published in Science, chromothripsis has been identified in approximately one in four human cancers, and is particularly common in aggressive tumour types including certain bone cancers, glioblastoma, and small cell lung cancer.

Understanding that N4BP2 is the enzyme responsible opens a path toward targeting it therapeutically — potentially preventing the chromosome shattering that turns a pre-cancerous cell into a fully malignant one with catastrophic genomic complexity.

Precision Oncology: Treating the Mutation, Not the Organ

The most consequential shift in cancer treatment over the past two decades has been the move from organ-based treatment — chemotherapy designed for “breast cancer” or “lung cancer” — toward mutation-based treatment designed for any cancer that carries a specific driver mutation, regardless of where it originated.

According to the American Association for Cancer Research’s 2026 forecasts, 2026 is being seen as a year where novel chemistry meets earlier care, guided by precision models that move beyond DNA-only thinking. Experts see particular promise in chemical inducers of proximity — a new class of molecules that can be used to address previously undruggable cancer targets by forcing proteins that promote cancer to interact with degradation machinery inside the cell.

As explored in our article on gene editing in 2026, CRISPR-based approaches are increasingly being applied to cancer — both as research tools for identifying which genes cancer cells depend on, and as potential therapeutic agents that could target cancer-specific mutations with a precision that conventional drugs cannot match. CAR-T cell therapy, which engineers immune cells to recognise and destroy cancer cells, has already produced remarkable results in blood cancers and is being investigated for solid tumours.

The personalisation of cancer treatment is also being transformed by tumour mutational burden analysis — sequencing a tumour’s entire genome to identify which mutations are present and which drugs are most likely to be effective against them. According to SmartCancer’s 2026 precision oncology review, this approach allows clinicians to distinguish driver mutations that actively promote tumour growth from passenger mutations that are genetically neutral — focusing treatment on the mutations that actually matter.

Cancer as a Disease of Aging

One of the most important but underappreciated aspects of cancer biology is its intimate connection to aging. The vast majority of cancers are diseases of aging — their incidence rises exponentially with age, and this is not simply because older people have had more time to accumulate mutations.

Aging and cancer share fundamental mechanisms. The telomere shortening that drives cellular senescence in aging tissue also creates the genomic instability that initiates cancer — when critically short telomeres are misidentified as broken DNA ends and repaired incorrectly, they can fuse chromosomes together, generating the kinds of massive rearrangements that drive malignant transformation. The accumulation of senescent cells in aging tissue creates a pro-inflammatory environment — through the senescence-associated secretory phenotype — that actively promotes tumour growth and invasion.

The epigenetic changes that accumulate with age — the drift in methylation patterns, the gradual reorganisation of chromatin — are strikingly similar to the epigenetic disruptions found in cancer cells. Studies show that age-related epigenetic changes may prime cells for malignant transformation by silencing tumour suppressor genes in the same way that cancer-specific epigenetic events do. Cancer and aging are not parallel processes. At the molecular level, they are deeply intertwined.

What Scientists Say

According to Keith Flaherty of Massachusetts General Hospital, speaking in the AACR’s 2026 expert forecast, “the novel chemistry advances that will help with early interception of cancer” are the most exciting development on the near-term horizon. The goal, he explained, is to identify and target pre-malignant cells — cells that carry driver mutations but have not yet become fully cancerous — before the tumour has established itself. Intercepting cancer at this stage would transform survival rates for many tumour types.

Researchers at the Van Andel Institute, describing their cancer epigenetics programme in February 2026, noted that cancer’s epigenetic errors “offer important opportunities for treatment” precisely because they are not permanent. Unlike DNA mutations, epigenetic silencing can potentially be reversed — and several approved epigenetic drugs are already demonstrating that reversing these changes can re-sensitise tumours to other therapies.

According to SmartCancer’s 2026 precision oncology review, cancer genomics now allows clinicians and researchers to identify driver mutations that actively promote tumour growth, distinguish them from passenger mutations with little biological impact, and select targeted therapies with a precision that was unimaginable two decades ago. Scientists have observed that this shift from empirical to rational cancer treatment — from treating tumour type to treating tumour genotype — represents the most important structural change in oncology since the development of chemotherapy.

Frequently Asked Questions

Is cancer caused by genetics or environment?

Both. Cancer requires genetic mutations, but those mutations can be caused by inherited factors, environmental exposures, or the natural errors that accumulate through normal cell division over time. According to research, approximately 5 to 10 percent of cancers are caused by inherited mutations in genes like BRCA1, BRCA2, or TP53. The remaining 90 to 95 percent arise from mutations acquired during a person’s lifetime, driven by factors including tobacco smoke, UV radiation, viral infections, chemical exposures, and random DNA replication errors. The risk of most cancers increases significantly with age, reflecting the cumulative accumulation of mutations over decades.

What is the difference between a driver mutation and a passenger mutation?

A driver mutation is one that directly contributes to cancer development by giving a cell a growth or survival advantage. Passenger mutations are genetic changes that have accumulated in a cancer cell but do not themselves promote cancer growth — they are along for the ride. Modern cancer genomics focuses on identifying driver mutations because they are the targets most likely to respond to treatment. According to precision oncology databases, the number of driver mutations in a typical tumour ranges from two to eight, while the total number of mutations can be in the thousands or tens of thousands.

Why do cancer cells become resistant to treatment?

Cancer cells evolve under the selective pressure of treatment. When a drug kills most cells in a tumour, any cells that happen to carry mutations conferring resistance to that drug survive and proliferate — replacing the sensitive cells with a drug-resistant population. This evolutionary process mirrors natural selection. Studies show that virtually all advanced cancers eventually develop resistance to targeted therapies, which is why combination approaches — attacking multiple targets simultaneously — and next-generation drugs designed to overcome known resistance mechanisms are central focuses of current oncology research.

What is chromothripsis and why does it matter?

Chromothripsis is a catastrophic event in which a chromosome is shattered into dozens or hundreds of fragments and then randomly reassembled. According to research published in 2026, the enzyme N4BP2 is responsible for triggering chromothripsis. The process is found in approximately one in four human cancers and can simultaneously inactivate multiple tumour suppressor genes and amplify multiple oncogenes in a single event — dramatically accelerating cancer development. Identifying the enzyme responsible opens potential therapeutic approaches to prevent or treat the most genomically complex cancers.

How is genetic testing used in cancer treatment?

Genetic testing in cancer takes two main forms. Germline testing analyses DNA from blood or saliva to identify inherited mutations — such as BRCA1 or BRCA2 mutations — that significantly increase cancer risk. Somatic or tumour genetic testing analyses DNA from a biopsy of the tumour itself to identify the specific mutations driving that individual’s cancer. The latter is the basis of precision oncology — matching specific drugs to specific mutations. According to 2026 guidelines from leading oncology organisations, tumour genomic testing is now standard of care for many advanced cancers, and is increasingly being used earlier in the treatment pathway.

Further Reading

Sources

• Jackson Laboratory (March 18, 2026) — The Hallmarks of Cancer 2026 Edition
• ScienceDaily (March 3, 2026) — Scientists Find the Genetic Switch That Makes Pancreatic Cancer Resist Chemotherapy (GATA6)
• ScienceDaily (February 17, 2026) — Mysterious RNA Led Scientists to a Hidden Layer of Cancer
• ScienceDaily (February 16, 2026) — Scientists Uncover Enzyme Behind Chromosome-Shattering Event in Cancer (Chromothripsis / N4BP2)
• Van Andel Institute (February 4, 2026) — Cancer Research in 2026: What Is New and What Is Next
• American Association for Cancer Research (January 8, 2026) — Experts Forecast Cancer Research and Treatment Advances in 2026
• SmartCancer (April 2026) — Genetics, Genomics and Precision Oncology 2026
• Wikipedia — Hallmarks of Cancer
• Wikipedia — Chromothripsis

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About the Author

Baryon is the founder and editor of Web News For Us. Driven by a deep fascination with the biggest unanswered questions in science — from quantum physics and cosmology to the nature of consciousness and the genetic code written into every living cell — he has spent years studying modern physics, biology, and the history of scientific thought. He covers Science & AI, Space, Genetics & Research, and the timeless wisdom of history’s greatest thinkers & mystics.

If you have ever looked at the night sky and felt — that pull to understand what is out there or the wonder of an entire universe coiled inside your genes, you are in the right place.