Precision Oncology is an approach to cancer care that uses detailed information about an individual's tumour and clinical circumstances to select prevention, diagnostic, prognostic or therapeutic strategies. Molecular information can include genomic alterations, gene expression, protein expression, epigenetic features and other biomarkers, while clinical precision also considers tumour type, stage, previous treatments and patient-specific characteristics. The central concept is not that every patient receives a completely unique treatment, but that treatment decisions are refined by biologically and clinically relevant differences between cancers. Precision Oncology has developed alongside advances in cancer genomics, pathology, sequencing and molecularly targeted drug development.
A major foundation of Precision Oncology is molecular profiling. Tumour cells accumulate genetic and epigenetic changes during malignant transformation and subsequent evolution, and some of these changes drive growth or create vulnerabilities that can be therapeutically exploited. Testing can identify actionable alterations, resistance mechanisms, inherited predisposition markers or biomarkers associated with treatment response. Techniques include targeted DNA panels, broader sequencing, RNA analysis, copy-number assessment, protein-based assays and other molecular methods. Testing may use a tumour biopsy, resection specimen or, in some circumstances, circulating tumour DNA from blood. The appropriate test depends on the cancer, clinical question, availability and evidence supporting its use.
Precision Oncology distinguishes between different biological roles of molecular alterations. A driver alteration contributes materially to tumour development or maintenance, whereas a passenger alteration may be present without being responsible for malignant behaviour. An actionable alteration is one for which an intervention has sufficient evidence or an appropriate clinical-trial rationale. A predictive biomarker provides information about the likelihood of response to a particular treatment, while a prognostic biomarker primarily provides information about disease outcome independently of a particular treatment. These distinctions are essential because the detection of a mutation does not automatically establish that a targeted drug will benefit the patient. Molecular interpretation must therefore integrate laboratory findings with clinical evidence.
The practical value of Precision Oncology is particularly visible in cancers with well-established molecularly defined subgroups. HER2 amplification or overexpression can identify breast cancers suitable for HER2-directed treatment, while specific alterations in genes such as EGFR or other signalling components can guide treatment selection in subsets of lung cancer. NCI describes examples including BCR-ABL-directed therapy in particular leukaemias, HER2-directed therapy in breast cancer and EGFR-directed treatment in selected lung cancers. These examples demonstrate that the molecular abnormality can sometimes provide more therapeutically relevant information than the broad anatomical label alone.
Precision Oncology is broader than simply ordering a genomic test. Its successful implementation requires validated laboratory methods, appropriate specimen collection, bioinformatic interpretation, clinically reliable databases, multidisciplinary review, access to matched treatments or trials and mechanisms for reassessing disease as it evolves. A molecular finding can have different meanings depending on tumour type, allele frequency, co-occurring alterations and clinical context. Tumour heterogeneity further complicates interpretation because a biopsy samples only part of the malignant population. A result reported as “no actionable alteration detected” does not necessarily mean that no biologically important alteration exists; it may reflect assay limitations, insufficient tumour material or incomplete knowledge of cancer biology.
Precision Oncology has important limitations and equity implications. Not every cancer contains a known actionable alteration, and not every actionable alteration has an approved or accessible therapy. Some molecular findings are uncertain in significance, and treatment response can vary even among tumours carrying the same alteration. Genomic testing can also identify inherited variants that have implications for relatives, requiring appropriate interpretation and genetic counselling where relevant. Access to comprehensive molecular diagnostics, specialist expertise, clinical trials and expensive medicines varies between health systems. Consequently, the scientific potential of Precision Oncology does not automatically translate into equal clinical benefit across populations.
The field has evolved from single-biomarker testing towards increasingly comprehensive molecular characterisation and adaptive treatment strategies. Clinical trials can be organised around molecular alterations rather than solely around anatomical tumour sites, while serial sampling can investigate changes that occur under treatment pressure. Liquid biopsy and circulating tumour DNA are being studied for applications such as treatment monitoring and detection of molecular recurrence, although their clinical roles vary by cancer and indication. Precision Oncology also increasingly incorporates resistance biology, because treatment may select tumour populations that differ from those present at diagnosis.
Precision Oncology should be distinguished from personalised medicine in its broadest sense. Personalised medicine can encompass preferences, lifestyle, comorbidities, pharmacological characteristics and other individual factors, whereas Precision Oncology particularly emphasises tumour and patient biology as a basis for cancer decisions. It should also not be confused with targeted therapy: targeted therapy is a treatment modality, while Precision Oncology is the broader clinical framework that can use molecular information to choose targeted treatment, endocrine treatment, immunotherapy, conventional therapy, surveillance or clinical trials. Its long-term significance lies in connecting increasingly detailed biological knowledge with evidence-based decisions while recognising the continuing uncertainty, heterogeneity and accessibility constraints inherent in cancer medicine.
