Early Kidney Cancer Detection Made Possible with a Simple Blood Test
By Ruchi Jhonsa. Ph.D.
Early detection of cancer is a critical factor in increasing the success of cancer therapies. Unfortunately, cancers are not that easy to detect as early small tumors cause no symptoms and are mostly found by chance in body scans performed for a different reason. About 35 percent of kidney cancers are diagnosed only after they have spread to other parts of the body leading to difficulties in treatments. A new diagnostic method developed by scientists at Dana Farber Cancer Institute in Boston helps detect cancer early in the development with 100% accuracy.
The traditional methods of detection involve high-tech imaging and tissue biopsies. However, these techniques are invasive and detect cancer when it is already too late to achieve a meaningful cure. A less invasive approach is to use blood samples. Very early tumors release whole cells, proteins, microvesicles, or DNA in the blood, which can be detected by nanotechnology sensors or high throughput sequencing. Although these techniques work for early detection of some cancers, most of them don’t work for kidney cancers as they don’t shed as many cells or DNA as other tumors.
A new detection method, cfMeDIP-seq developed at Dana Farber, is trying to overcome this difficulty by using a highly sensitive detection method that identifies abnormal methyl chemical tags on the DNA shed by kidney cancer cells. When healthy cells are transformed into cancer cells, a series of changes happen on the genetic material that can entirely change certain bases on the DNA or modify it in a certain way by adding chemical groups. These modifications in the form of methyl groups are normally present in a specific pattern on the DNA of healthy cells. However, this methylation pattern changes when a cell turns cancerous. This new method is trying to catch these abnormal patterns to detect new cancer early on. This method is different from other DNA-based liquid biopsy tests that identify specific mutations linked to cancers instead of the chemical tags.
“Kidney cancer is one of the hardest tumors to detect because it doesn’t shed as much DNA as other tumors,” said Matthew Freedman, MD, a medical oncologist at Dana-Farber and co-senior author of the report. “That’s where this test performs really well” because it can identify abnormal patterns in small amounts of tumor-shed DNA. “And it’s a proof of principle that early-stage disease is detectable.”
The blood samples were collected from 99 patients with early and advanced kidney cancer, 15 patients with stage IV urothelial bladder cancer, and 28 healthy cancer-free participants. The test could distinguish blood samples of cancer patients from cancer-free participants with 100% accuracy. However, the test didn’t work as well with the urine samples and needs further validation. “Hopefully, we can scale this to a much larger level and detect cancer earlier so we can act earlier,” said Toni Choueiri, MD, a co-senior author of the study and the director of the Lank Center for Genitourinary Oncology at Dana-Farber.
Small, early kidney tumors usually cause no symptoms and are increasingly found incidentally in scans of the abdomen performed for another purpose. However, there is no imaging or other screening test recommended for the general population to look for early kidney cancers. Initially, a test based on the method described in the new report might be used to screen people with a family history of kidney cancer, or who had previous kidney cancer, said Choueiri. “We need to be specific first, before making it totally mainstream,” he said.
The study is published as a brief communication in Nature Medicine.
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