Researchers at Princess Margaret Cancer Centre in Toronto are conducting a large-scale trial called SHERLOCK to determine if a blood test can detect microscopic traces of cancer remaining after treatment.The test, known as a liquid biopsy, analyzes cancer DNA in the blood, which can be present in amounts too small to be detected by CT scans.

If positive, patients may receive experimental immunotherapies to prevent cancer recurrence, while a negative result could allow the cessation of unnecessary treatments.

The study involves 7,000 patients who have completed cancer therapies, with long-term follow-up over five years to assess the test's predictive accuracy.Lead investigator Dr.Lillian Siu emphasized that while promising, liquid biopsies are not yet standard practice.Patient Paul Lonergan shared how participation in a similar trial helped manage his throat cancer recurrence.

Experts like Gillian Vandekerkhove praised the SHERLOCK trial's broad focus on multiple cancer types, though acknowledged its observational nature requires further trials.The research aims to alleviate patients' fears of cancer returning by providing clearer post-treatment monitoring.