New York, March 23 Radiotherapy may leave behind microscopic cancer even when scan images suggest the tumour is gone, and this “residual disease” is more common than expected and is linked to worse long-term outcomes, researchers have warned.
Dr Muzamil Arshad from the University of Chicago Medical Center and colleagues highlighted this growing concern in cancer care, in a new editorial published in Oncotarget journal.
Their perspective calls for a rethinking of how treatment success is judged and how cancer is followed up after therapy.
Radiotherapy, especially a form known as stereotactic ablative radiotherapy (SABR), is widely used to treat cancers in the lung, liver, prostate, and other organs.
SABR delivers high-dose radiation with outstanding precision and often shows excellent results on scans.
However, the authors highlighted that relying only on imaging may not provide a complete picture.
Months or even years later, follow-up biopsies frequently reveal cancer cells that scan imaging tests were unable to identify.
“Residual cancer is identified on histology in 40 per cent of lung, 57–69 per cent of renal cell, 7.7–47.6 per cent of prostate and 0–86.7 per cent of hepatocellular carcinoma,” said authors.
This gap between what scans show and what tissue analysis finds can have serious consequences.
Studies across several cancer types have shown that patients with residual disease — even if small — are more likely to experience cancer recurrence and shorter survival.
This pattern holds true for rectal, cervical, prostate, and liver cancers, among others. In some cases, not destroying the tumour completely may allow it to spread to distant organs.
The authors pointed out that a complete response on scan imaging does not necessarily indicate the complete disappearance of the tumour.
The editorial encouraged the cancer care community to look beyond the scan images. Residual cancer may remain even when imaging looks clear, and recognising this hidden threat is key to improving long-term outcomes.
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