Breast cancer recurrence is usually discovered only when tumours grow large enough to appear on imaging or cause symptoms. Researchers at Lund University have validated a blood-based alternative: a test that profiles the genetic alterations in each patient's tumour and then tracks those alterations as fragments of circulating tumour DNA in the blood. In a prospective observational study, 136 patients treated with chemotherapy and surgery gave samples at diagnosis, during treatment, after surgery and through up to six years of follow-up.
The results, published in EMBO Molecular Medicine by a team including senior author Lao Saal, were striking. Tumour DNA was detectable in nearly 90 per cent of patients before treatment. Among those who later developed metastatic disease, the test signalled recurrence a median of 13.8 months before it was clinically evident. Roughly 13 per cent of patients showed no clear decline in tumour DNA during pre-surgical treatment, a pattern strongly linked to relapse, and the marker proved more informative than pathological complete response, the current standard measure.
The method trades genomic depth for speed and affordability, which the researchers argue is the right compromise for routine monitoring. Earlier warning could allow intervention for high-risk patients before metastases take hold, while persistently negative results might spare low-risk patients unnecessarily intensive therapy. The test was developed with the Lund-founded company SAGA Diagnostics, and clinical colleagues at Skåne University Hospital stress that treatment-changing applications must now be demonstrated in interventional trials.