Can a Blood Test Replace the More Invasive Biopsy to Detect Cancer?

New research published in the journal Physical Biology concluded that an advanced blood test that detects and analyzes circulating tumor cells in the blood of cancer patients was highly sensitive and may provide information comparable to that obtained in surgical biopsies when tested in 5 settings. The new test called HD-CTC labels cells in a patient’s blood in a way that distinguishes circulating tumor cells from ordinary red and white blood cells. It then uses a digital microscope and an image-processing algorithm to isolate the suspect cells with sizes and shapes unlike those of healthy cells so that the pathologist can examine the images of the suspect CTC cells to eliminate false positives. This process is similar to that used by a pathologist with biopsy slides.
To test the technology, five studies were carried out in California, Montana and in the Netherlands.
In the first study researchers examined 83 advanced cancer patients using HD-CTC to document the sensitivity and accuracy for different cancer types. Researchers found that the test detected five or more CTCs per milliliter of blood in 80% of patients with metastatic prostate cancer, 70% of those with metastatic breast cancer, 50% of those with metastatic pancreatic cancer and no healthy subjects. The current gold-standard CTC test (CellSearch) was notably less sensitive in detecting tumor cells in the samples.
Most patients whose CTC count surpassed the detection threshold also showed small aggregates of CTCs, which cancer biologists call “microtumor emboli” that are believed to be incipient metastatic tumors and triggers for blood clots that often kill advanced cancer patients. In study 2, scientist showed that HD-CTC could detect these aggregates in 43% of 71 patients with advanced prostate, lung, pancreas, and breast cancers and in none of a group of 14 healthy subjects.
In the third study, HD-CTC was used to compare circulating tumor cells from prostate cancer patients with cells from prostate cancer cell lines often used as convenient models for prostate cancer biology in the lab. Significant differences were found between the two classes of cells, in their cell morphology and in the way they were labeled by HD-CTC fluorescent tags. These results underscore the need when carrying out research to use cells from cancer patients and not model cancer cells that may be different from the real thing.
Researchers performed HD-CTC tests on 28 patients with advanced non-small cell lung cancer over periods up to a year in the fourth study. They were able to detect CTCs in 68% of the sample, and the numbers of detected CTCs tended to go up as other measures showed cancer progression.
In the last study the researchers used HD-CTC in 78 patients who had just been diagnosed with various stages of non-small cell lung cancer and that demonstrated that they could detect CTCs even in patients with early stage cancer.
The five studies not only demonstrated the accuracy and effectiveness of the test for a number of different cancer types, it began to explore the utility of the technology for diagnosing and monitoring patients and improving cancer research in the laboratory.

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