From using fluid in the lungs to better understand the potential of immunotherapy treatments in lung cancer, to tracking circulating tumor cells in prostate cancer, to conducting RNA sequencing of cancer cell clusters from the blood of pancreatic cancer patients, to finding new ways to biopsy tissue from patients who may have esophageal cancer, a series of studies from the Perelman School of Medicine at the University of Pennsylvania have demonstrated the promise of new diagnostic methods.
Three of the studies focus on liquid biopsies, an innovation which uses blood tests instead of surgical procedures in hopes of detecting cancer.

The first study is focused on biopsies and immunotherapy treatments for non-small cell lung cancer ( NSCLC ), the most common form of the disease.

One of the most promising immunotherapies for NSCLC targets the PD-1/PD-L1 pathway, which is known to suppress the immune system's ability to fight off cancer. These therapies inhibit this pathway, allowing the body to fight back. Currently, patients must undergo a biopsy to determine if they are candidates for this therapy.
Because obtaining biopsy tissue may cause patient discomfort and can sometimes be difficult or impossible to obtain due to location of the tumor, Penn researchers wanted to find a less invasive way to test these patients. They focused on malignant pleural effusions, fluid surrounding the lungs, which is a frequent complication in patients with advanced NSCLC.

The study evaluated the fluid from 66 patients. Researchers found circulating tumor cells ( CTCs ), cancer cells that have moved into the blood stream, in 63 of them.
Twenty-three percent of patients with a malignant pleural effusion were found to have detectable PD-L1 expression using this technology, which is similar to previous studies.

The results have shown this method may work on a larger scale, but that more research is needed.

Circulating tumor cells were also at the center of a study focused on clusters of those cells in the blood of prostate cancer patients.

Researchers at Penn Medicine and also at other institutions have shown that circulating tumor cell clusters, a phenomenon in which CTCs move through the blood in groups rather than alone as a single CTC, are particularly dangerous in terms of metastatic spread, or cancer spreading throughout the body.
The ability to find and understand those clusters is crucial.

Researchers looked at 55 samples from 29 different patients. They found clusters of CTCs in 13 of the 29 patients ( 44.8% ) and 19 out of the 55 samples ( 34.5% ).

The next step is to compare these cluster counts with other blood-based measures like prostate-specific antigen ( PSA ) and chromogranin A ( CgA ) to see if the number of clusters correlates with a more aggressive disease.

Source: American Association for Cancer Research ( AACR ) Annual Meeting, 2017

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