New liquid biopsy method detects early kidney cancer

A novel liquid biopsy method has been found to detect kidney cancers with high accuracy, including small, localised tumours that are often curable but for which no early detection method currently exists. That’s according to a new study conducted by Dana-Farber Cancer Institute scientists, who published their results in the journal Nature Medicine.

It’s estimated that 73,750 new kidney cancer cases will be diagnosed in 2020 and about 14,830 will die of the disease. About 35% of cancers are diagnosed only after they have spread beyond the kidney and are more difficult to treat — this is because small, early kidney tumours usually cause no symptoms and increasingly are found incidentally in scans of the abdomen performed for another purpose.

Non-invasive liquid biopsies, which search for cancer-related DNA shed by tumours into blood or other body fluids, are moving rapidly towards clinical use as a means of early detection for some kinds of tumours. However, kidney cancer remains one of the hardest tumours to detect, because it doesn’t shed as much DNA as other tumours. This is where the method tested by the Dana-Farber scientists performs well, because it can identify abnormal patterns in small amounts of tumour-shed DNA.

The technical name for the testing method is cfMeDIP-seq, which stands for cell-free methylated DNA immunoprecipitation and high-throughput sequencing. Where other liquid biopsy methods search for mutations in tumour-shed DNA that reveal the type and location of cancer, cfMeDIP-seq detects abnormal methylation — the addition of chemical tags to DNA, which doesn’t alter their genetic code but can affect their function.

The method was tested on samples from 99 patients with early and advanced kidney cancer; 15 patients with stage IV urothelial bladder cancer; and 28 healthy, cancer-free control subjects. The test proved nearly 100% accurate when used with blood samples to distinguish patients with kidney cancer from those known to be free of kidney cancer, indicating that detection of early-stage disease was possible. The method achieved less accuracy in testing urine samples, but the researchers believe that its performance can be improved through technical and computational optimisation — which could lead to a more accurate urine test that is even less invasive than a blood draw.

If validated in larger trials and applied widely, the test could find more early kidney cancers when they haven’t spread, thus reducing the mortality of the disease. Initially, it might be used to screen people with a family history of kidney cancer, or who had a previous kidney cancer.

“Hopefully we can scale this to a much larger level and detect cancer earlier so we can act earlier,” said Dr Toni Choueiri, a co-senior author of the study.

“We need to be specific first, before making it totally mainstream.”

Image credit: ©stock.adobe.com/au/bluebay2014

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