By Tatini Rakshit
As diseases go, cancer is deadly. Its early detection, however, can make a huge difference to the patient’s life. Early diagnosis can help prevent metastasis, which is the spread of the cancer to other parts of the body. It improves the chances of successful treatment, reduces treatment costs, and increases survival rates.
When detected early, cancer is also often treatable with less aggressive methods such as targeted therapies, immunotherapy and active surveillance. These make the patient’s quality of life better than the more aggressive alternatives, surgery and chemotherapy.
Given all this, the emergence of liquid biopsy for cancer screening is good news for cancer patients.
Different cancers require specific screening tests to detect abnormalities before symptoms appear. Some of the most commonly used screening methods include mammograms, which use X-rays to detect breast cancer; pap smears and HPV tests, which screen for cervical cancer; and colonoscopy, along with stool-based tests, to identify colorectal cancer.
Unlike traditional biopsies, which require the removal of tissue samples, liquid biopsy is a non-invasive approach that analyses biomarkers—biological indicators of disease—in bodily fluids such as blood, saliva, and urine. This allows doctors to detect cancer at an early stage, monitor how a patient responds to treatment, and identify minimal residual disease, which refers to small amounts of cancer cells that remain after treatment and could potentially lead to a relapse.
The method relies on several biomarkers to detect cancer. For example, tiny fragments of genetic material known as circulating tumour DNA or ctDNA are released by cancerous cells into the bloodstream. There are also circulating tumour cells, meaning cancerous cells that have broken away from the tumour and are found in the blood. Liquid biopsies look for both.
Other such biomarkers include extracellular vesicles and exosomes, which are small particles released by cells that contain genetic material and proteins, as well as microRNAs, proteins, and metabolites, all of which can provide critical information about cancer presence.
Some liquid biopsy tests have already received FDA approval for clinical use. Examples include Guardant360 CDx, FoundationOne Liquid CDx and the ExoDx Prostate Test.
AI and personalised medicine
Ongoing clinical trials are currently refining liquid biopsy technology.
Researchers at the University of Queensland have developed a blood test to detect early-stage ovarian cancer, demonstrating a 94 percent accuracy rate with a false-positive rate of only 4 percent, meaning it rarely misidentifies healthy individuals as having cancer. Another promising study, known as the EXONERATE study, is investigating a liquid biopsy method to predict progression-free survival, overall survival, and treatment response rates in patients with metastatic colorectal cancer, a form of advanced colon cancer that has spread to other parts of the body.
Saliva-based liquid biopsy is also emerging as a promising tool for detecting and monitoring cancers of the oral cavity, head, neck and lungs. By analysing tumour DNA, RNA, proteins and exosomes in saliva, doctors can detect early signs of cancer using a simple, non-invasive test.
Several key biomarkers are being studied in this method, including mutations in certain genes which are commonly associated with cancer development.
Compared to traditional biopsies, saliva-based tests are painless, cost-effective, and allow for continuous cancer tracking, making them a valuable tool in personalised medicine. As this technology advances, costs are expected to decrease, improving accessibility.
Additionally, artificial intelligence is helping to refine these tests by reducing false positives, minimising overdiagnosis and improving overall accuracy.
Liquid biopsy is also transforming personalised medicine by enabling real-time, non-invasive cancer monitoring, guiding targeted therapy decisions, and predicting how well a patient will respond to treatment.
Personalised medicine, also known as precision medicine, is an approach that tailors treatment based on an individual’s unique genetic makeup, lifestyle and environment. Rather than applying a “one-size-fits-all” approach, doctors use genetic information to determine the most effective course of treatment.
In cancer treatment, genetic testing can identify specific mutations which are linked to breast cancer or lung cancer. This information allows doctors to prescribe targeted therapies that attack cancer cells more precisely, reducing side effects, as compared to traditional chemotherapy.
Personalised medicine is also being applied in pharmacogenomics, a field that studies how a person’s genetic profile affects their response to medications. By understanding genetic variations, doctors can predict which drugs will work best for a patient while reducing the risk of adverse reactions.
As genomics, AI, and molecular biology continue to advance, personalised medicine is reshaping healthcare by improving early disease detection, tailoring treatments to individual needs, and ultimately improving outcomes for patients.
Who should get tested?
While the emergence of new methods for cancer screenings is invaluable in detecting cancer early, the need for such screenings depends on individual risk factors, medical history, and discussions with healthcare providers.
One of the key challenges of cancer screening is the potential for false positives, where a test incorrectly suggests the presence of cancer, leading to unnecessary stress and additional medical procedures. Overdiagnosis is another concern, as some screenings detect slow-growing cancers that may never cause harm, resulting in unnecessary treatment. Some cancers are so slow-growing that we can live with them without them killing us; they are indolent. This is famously true for both prostate cancer and thyroid cancer.
Most people do not require cancer screenings until their forties, as the risk of developing cancer increases with age due to genetic, lifestyle, and environmental factors. However, certain individuals face a higher risk and may require earlier or more frequent screenings.
Those with a family history of cancer or inherited genetic mutations have a significantly increased risk of developing cancer. Additionally, lifestyle factors such as smoking, heavy alcohol consumption, obesity, and physical inactivity increase the chances of developing cancers like lung, liver, breast, and colorectal cancer. Exposure to harmful chemicals, radiation, and chronic conditions such as diabetes, inflammatory diseases, and HPV infection can also heighten the risk of cancer.
Women with hormonal risk factors, such as late menopause, early menstruation, or having children later in life, face an increased likelihood of developing breast and endometrial cancer, while men over 50 are more susceptible to prostate cancer.Dietary habits also play a role, as consuming high amounts of processed meats and red meats has been linked to colorectal cancer.
Maintaining a healthy lifestyle, avoiding known carcinogens and undergoing screenings if one is at risk can significantly reduce the danger of cancer.
Dr Tatini Rakshit is an Assistant Professor at Shiv Nadar Institution of Eminence, Delhi-NCR, and a former Postdoctoral Fellow of the National Cancer Institute, National Institute of Health, USA.
Originally published under Creative Commons by 360info™.
