A simple blood test may help determine whether your cervical cancer is responding to treatment or whether it has relapsed, shows early research by doctors from the All India Institute of Medical Sciences, Delhi.
They found fragments of the DNA of human papillomavirus (HPV) — the virus responsible for the vast majority of cervical cancer cases — circulating in the blood, with their levels correlating with the size of the tumour. As patients began treatment, these levels dropped, indicating how the cancer cells were responding to treatment.
The findings have been published in the Nature group journal, Scientific Reports.
Why is this study significant?
This could be a game-changer as cervical cancer is the second most common cancer among women in India with more than 95 per cent cases linked to persistent infection with certain high-risk strains of HPV. As normal screening and follow-ups are cumbersome and costly, a blood test could be a cheaper alternative.
“Cancer patients have to repeatedly undergo tests and scans to keep track of whether their cancer is responding to treatment and whether they remain cancer-free afterwards. Using the blood test instead can reduce this cost, with only those who have elevated biomarkers undergoing the full body scans,” said Dr Mayank Singh, one of the authors and associate professor of medical oncology at AIIMS. “Sometimes the blood biomarkers can show up before tumours become visible on scans — so this may even help in detecting relapses sooner as well,” he added.
What the study found
Doctors used a very sensitive molecular test to detect trace amounts of DNA of the two most common high-risk HPV strains — HPV16 and HPV18. They selected 60 cervical cancer patients who had not started their treatment. They also collected samples from 10 healthy women to compare the results with. The average level of circulating viral DNA in the cancer patients was 9.35 ng/µL (a measure of concentration) while it was 6.95 ng/µL among healthy women. The doctors were also able to show that after three months of treatment, the level of circulating DNA reduced to 7 ng/µL.
Once proven in a larger cohort, the test may be used for initial diagnosis as well as early detection because 90% of patients who reached the hospital were already in the second or third stages of the disease. The likelihood of survival reduces with cancers detected in later stages.
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As of now, the most common test for cervical cancer screening is pap smear, where the cells collected from the surface of the cervix on a swab are studied under the microscope to detect changes. The other commonly used test, especially in resource-scarce areas, is visual inspection with acetic acid. A solution with 3-5% concentration of acetic acid is applied on the cervix, which reacts with pre-cancerous or cancerous cells to give a whitened appearance.
For the final diagnosis and staging of the cancer, patients have to undergo a biopsy. This is also where the blood test may come in handy.
There were 1.27 lakh cervical cancer cases and 79,979 deaths in 2022 in India, according to data from the World Health Organisation’s Global Cancer Observatory. The overall survival rate of cervical cancer in India is around 46 per cent, according to the study.
The good thing is cervical cancer is one of the only vaccine-preventable cancers. The government is considering cervical cancer vaccination in girls between the ages of nine and 14.
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