Saliva based liquid biopsy, one of the upcoming innovative methods for testing oral cancer may prove to be a game changer for diagnosis, early intervention, and management for oral cancer. Leading experts, researchers, and organisations gathered and deliberated on the same at the 4th edition of Oral Cancer Task Force (OCTF) Conference held in Bengaluru on 27th July 2023. Dr Vamsi Veeramachaneni, chief scientific officer at Strand Life Sciences, Bengaluru, proposed that this non-invasive testing method for oral cancer could diagnose nearly 80 percent of this cancer cases.
Oral cancer, largely caused by tobacco and alcohol use, can start in the mouth, back of the mouth, tongue, throat, larynx (voice box), inside and around the nose, cheeks, and on the lips too.
Symptoms of Oral Cancer
The early diagnosis and intervention of oral cancer remains a challenge unlike other cancers such as breast cancer, or prostate cancer, say experts. This challenge is largely attributed to the difficulty in identifying symptoms, explains Dr Narayana Subramaniam, consultant & HOD, Head & Neck Surgical Oncology, Sri Shankara Cancer Hospital & Research Centre, Bengaluru. The symptoms are often mistaken for generic infections, dental troubles, gastric reflux or similar conditions. Lack of awareness is another contributing factor, he adds.
Dr Subramaniam lists down the symptoms:
- A sore, red or white patch in the mouth
- Lumps or bumps in the mouth or cheek or neck
- Loosening of teeth
- Blood-tinged saliva
- Difficulty opening the mouth
- Difficulty or pain in swallowing water and food
- Change in voice or hoarseness
Saliva-based liquid biopsy: a new testing method
Dr Veeramachaneni and his colleagues, in their 2021 study, stresses on the need for early intervention that increases the survival rate by 80 per cent as against 20-60 per cent during late-stage diagnosis.
Dr Subramaniam explains, “The most popular early screening method is a clinical examination that includes direct visualisation of the mouth and endoscopy of the throat and the voice box.”
To this, Dr Shivangi Gaur, Oral and Maxillofacial surgeon, Clove Dental, Noida, Uttar Pradesh, adds, “This is followed by a biopsy (a procedure in which the abnormal tissue is removed and tested under microscope which indicates histopathological results). She further adds that this is often complemented with contrast enhanced MRI (magnetic resonance imaging), CT (Computed Tomography) and PET (positron emission tomography) to understand metastasis (or the extent of the disease through the body).
The study further points out that traditional biopsy method, which is invasive, can give pain or discomfort. This can discourage people from early screening of oral cancer. Instead, a non-invasive and painless method can help overcome these limitations.
What is saliva-based liquid biopsy?
Dr Veeramachaneni explains, “In saliva-based liquid biopsy, the oral rinse sample is collected in custom tubes and stored at room temperature.” This rinse contains cell-free DNA and cells which have been dislodged from different parts of the body and lesions. This test identifies mutated genes through saliva samples, emphasises Dr Veeramachaneni.
Is saliva-based liquid biopsy useful?
While this test can only diagnose advanced stage cancer lesions at present, further research is needed to assess early detection among the high-risk population. “Liquid biopsy has been extensively used in identifying precancerous lesions for breast cancer, lung cancer and the like,” says Dr Gaur. If this new method can also detect precancerous lesions in oral cancer through saliva, it can help in early detection, adds Dr Gaur.
Dr Veeramachaneni adds that this test has high potential for assessing recurrence of cancer among people with minimal residual disease (MRD-Cancer cured people who may have small amounts of remnants of cancer cells after the treatment).” In this purview, Dr Subramaniam states that the preliminary data has been promising, however it needs to be validated in all high-risk individuals too (those with tobacco and alcohol use).”
Will people prefer this testing method?
When the symptoms (mentioned above) persist for over three weeks, one must be evaluated by an oncologist, advises Dr Subramaniam. To this, Dr Gaur adds, the advantage of saliva-based testing is that it is non-invasive. “The idea that those at risk (smokers and alcoholics) can just spit into this tool for saliva samples, which can be further tested, makes this test more viable,” says Dr Gaur. She adds, however, there is need for more research and more validation.
The time taken for the results is another advantage, says Dr Gaur. “The entire process from sample receipt to report dispatch takes approximately two weeks. However, this can be reduced to one week,” explains Dr Veeramachaneni. Dr Gaur adds, “If the test can take less time than a conventional biopsy, it can help.”
Talking about the pricing of the test, Dr Veeramachaneni emphasizes that cost is another factor that needs to be considered. While the costs are high now, this method can become more widely available in the near future with more support.
Takeaways
- The early diagnosis and intervention of oral cancer can increase the survival rate by 80 per cent.
- Clinical examination, biopsy, CT scan and MRI are the most prevalent testing methods for oral cancer.
- Saliva-based liquid biopsy is a new and promising testing method.
- The advantages of this method are its non-invasive and painless ways.
- The study needs more investigations and more conclusiveness.
