Introduction

Cancer was one of the most frightening diseases of the 20th century, and is becoming more common and persistent in the 21st century. According to the World Health Organisation (WHO), every one out of five people will develop cancer in their lifetime and the yearly cancer incidence is over 20 million cases in the world. Cancer means uncontrolled growth of cells. Since cancer is a complex and rapidly changing disease, traditional treatment strategies are often inadequate to address it. Conventional cancer treatments (chemotherapy, radiation, etc.) are standardised. Often, this type of treatment will not work for every patient.^1,2,3

Precision medicine is largely used to treat cancer and represents a revolutionary advancement in cancer treatment. The term precision medicine (PM) refers to a method that determines the most effective way to prevent or cure disease by taking into account a person's genetics, environment, and lifestyle. Another name for it is individualised or personalised medicine.²

Oncologists can create more individualised, focused, and possibly more successful treatment regimens because of precision medicine. It takes into account the patient's entire biology and living circumstances rather than only treating the illness.²

Precision medicine represents a shift from reactive therapeutic treatment to proactive, patient-specific solutions in the rapidly evolving world of oncology. There are promises of increased efficacy, decreased toxicity, and a more humane method of caring for and treating one of the most difficult diseases in existence.^1,2

Background

Conventional cancer treatment focused largely on the tumour's location, and therefore, patients with similar cancers were treated the same. This approach was usually not suited to patients, as they had individual differences in the tumour biology.³ 

With the introduction of genome sequencing and advances in molecular biology, including the Human Genome Project, scientists began to understand the underlying genetic alterations responsible for cancer and subsequently introduced a new approach: treating cancers according to the genetic aberration.^1,2

The platform of precision medicine is the transition from the organ-based model of care in cancer treatment to a mutation-based model of care.

Key components of precision medicine in cancer

Genomic profiling and molecular diagnostics

Genomic profiling helps to identify mutations, gene expressions, and biomarkers (e.g., BRCA1/2, EGFR, HER2, KRAS) that support tumour growth. Genomic profiling is accomplished through methods such as next-generation sequencing (NGS), PCR, and microarrays that will help to expose genetic changes.¹

Biomarker-driven therapy

While companion diagnostics are usually used to assess a patient's eligibility for a targeted-agent medication, predictive biomarkers assist in matching patients to the most effective therapy.¹

Targeted therapies

Targeted medications are created especially to stop particular biochemical pathways that cause cancer to progress; these medications are frequently referred to as "targeted agents." Monoclonal antibodies and tyrosine kinase inhibitors (TKI) are examples of targeted agents. Imatinib is used to treat chronic myeloid leukemia (CML), and trastuzumab is used to treat HER2-positive breast cancer. These are two examples of targeted-agent medications.^2,3

Immunotherapy and precision medicine

Precision immunotherapy includes checkpoint inhibitors (e.g., PD-1, PD-L1) and CAR-T cell therapy, which are based on the offending patient's immune system and tumour characteristics.¹

Pharmacogenomics

Pharmacogenomics studies the person-specific genetic makeup and drug response relationships among patients with reference to drugs, dosing, and the original intent of drug therapy: to minimise adverse drug reactions.²

Clinical applications and case studies

Key clinical applications are listed here:

Lung cancer

Drugs or other chemicals are used in targeted therapy to locate and target particular cancer cells. Targeted treatments, including osimertinib, alectinib, and crizotinib, are used in response to mutations in EGFR, ALK, and ROS1.⁴

Breast cancer 

Treatment is determined by HER2 status and hormone receptor (ER/PR) testing. Trastuzumab is effective in HER2-positive individuals. ER/PR-positive: tamoxifen and other hormone blockers are used to treat this condition.⁵

Colorectal cancer

Testing for KRAS and BRAF mutations directs treatment. Cetuximab and other anti-EGFR medications do not work on KRAS-mutant cancers. BRAF + MEK inhibitors may be effective in treating BRAF V600E mutations.⁶

Technologies supporting precision medicine

Bioinformatics and AI in analysing genomic data

Bioinformatics technologies offer important insights into the molecular foundations of health and disease by facilitating in-depth examination of a person's genetic composition. Targeted sequencing panels (TSP), whole exome sequencing (WES), and whole genome sequencing (WGS) are examples of high-throughput sequencing techniques like NGS that allow researchers to pinpoint particular genetic mutations and changes that propel the growth and spread of tumours.⁷

Algorithms for AI and machine learning help to find trends in clinical and genetic data, forecast the results of treatment, more precisely classify cancer subtypes, and automate pathology and imaging data analysis. AI helps oncologists make data-driven, individualised treatment decisions by improving diagnostic speed and accuracy.⁸

Liquid biopsy and circulating tumour DNA (ctDNA) detection

Rapid advancements in liquid biopsy technology, which allows for the molecular interrogation of liquid samples, have made it possible for routine clinical use in cancer patients as well as for the rapid expansion of research capabilities that are revealing the causes of malignant growth. Liquid biopsies offer a technique for extracting tumour-derived (circulating tumour DNA) information from bodily fluids and are minimally invasive.⁹

Cancer cells shed ctDNA into the circulation, which contains the same mutations as the tumour itself.¹⁰

Use of big data and clinical databases for predictive modeling

Precision oncology uses large data from genomic, clinical, and lifestyle sources to construct predictive models. These models aid in forecasting illness outcomes, treatment responses, and relapse chances, allowing for more precise and individualised therapy. Databases such as TCGA and cBioPortal provide large-scale data required for training these algorithms.⁸

Benefits of precision medicine in cancer

Precision medicine is multifaceted in that it can allow for approvals of new innovative treatment, change the way medicine interacts or is structured in the health care system, improve the selection of medications and targeted therapy, minimise side effects, increase patient compliance, enhance the focus of medicine from reactive to preventative, improve the cost-effectiveness of medicines, and reassure patients as they receive a medical product on the market.¹ 

By matching medicines to specific genetic and molecular characteristics of each tumour, precision medicine can improve patient outcomes and reduce the burden of trial-and-error prescribing. By targeting specific biomarkers, precision medicine will reduce the risk of unnecessary exposure to ineffective treatments. Emerging progressive biosensing devices, ctDNA, allow us to detect disease progression earlier and take action more quickly.^1,3

On top of enhanced quality of life and faster recovery times, individualised care enables patients to have a sense of agency over their treatment pathway. Widely, it maximises the efficient use of healthcare resources and accelerates the availability of new, focused drugs. 

Challenges and limitations

Like any new venture, precision medicine will have many hurdles. Besides being expensive, collecting and analysing the vast amounts of data will be very labour and expertise-intensive. Privacy and security of data are a big concern. The earliest turnaround time when processing data is 26 hours, still too late for acute care environments to make decisions. There is a need for capacity improvement, training healthcare workers in machine learning and AI, meanwhile enabling access to the best lab equipment.¹¹

Although there is much potential with precision medicine in oncology, dynamics such as the unequal access to new diagnostic types, especially in low- or middle-income countries, pose a challenge. Patients with rare mutations, or mutations that are not yet well understood, have fewer effective treatments available, in some cases being restricted to only tumours whose biomarkers are known. The long timelines associated with drug development are further impacted by clinical trial designs that are unable to accommodate very individualised treatment programs. While there has been progress made in integrating multi-omics data, the field still has limitations, such as different interpretations and standardisations of labs.²

Besides, patients may have anxiety about genetic risk information that is not associated with an evidence-based therapeutic mechanism, and there are ethical questions to ponder when treating unexpected genetic consequences. There is also difficulty evaluating safety and long-term benefit because of a lack of longitudinal follow-up evaluation on patient outcomes.^2,8

Future directions

The future of precision medicine in cancer is bound to converge with multi-omics via genomics, proteomics, and metabolomics to inform the comprehensive understanding of tumour biology. Efforts are also in the early stages with paediatric oncology, where precision could enhance survival, minimise long-term sequela, and so on. Artificial intelligence (AI) is likely to become an instrumental aspect of identifying the right treatment plan based on the analysis of multi-dimensional data accurately and quickly. Additionally, global collaboration, sharing of data, and conducting research with rare cancers will help close gaps in time and improve access to personalised care around the world.^8,11

FAQs

What is precision medicine in cancer?

Precision medicine utilises a patient's genetic, molecular, and clinical profile to personalise cancer treatment to maximise efficacy and minimise side effects.¹

How is it different from traditional cancer treatment?

Precision medicine does not use a "one size fits all" approach to treatment; it uses specific mutations or pathways that are unique to each patient's cancer.¹

What tests are available for precision medicine?

Genomic profiling, biomarker testing, and liquid biopsies are the best tests to identify actionable targets.¹

Is precision medicine for all cancer patients?

Not always, precision medicine works best when cancers have identifiable mutations or identifiable biomarkers linked to therapies that will be effective.¹

Summary

Precision medicine is changing the future of oncology by allowing targeted therapies based on a patient's genetic and molecular background. These therapies can change the course of cancer by positively enhancing outcomes and minimising side effects. For precision medicine to reach its ultimate potential and truly help cancer patients, ongoing research, ethical implementation, and equitable access are essential.