Blood reveals what the pancreas hides
Sky News – Pancreatic cancer may be detectable from 10 small molecules circulating in the blood, before the disease presents clear signs of its presence.
This was tested in a large international study evaluating a screening test that combines an RNA signature with a clinically used tumor marker, in an attempt to detect cancer at its early stages.
The study included 1,785 individuals from four countries, and its results were published in the journal Nature Medicine. Researchers tested the assay, known as PANCAN, for detecting pancreatic ductal adenocarcinoma, the most common type of pancreatic cancer.
The test detects a signature composed of 10 types of microRNA, small molecules involved in regulating gene activity, whose levels can change when tumors develop.
Researchers combined this signature with measurements of the carbohydrate antigen CA 19-9, a well-known tumor marker used to monitor some pancreatic cancer patients, but which is insufficient on its own for screening the general population or confirming diagnosis.
Combining these indicators yields an estimated probability of pancreatic cancer, aiming to help physicians identify who requires imaging or additional tests, rather than issuing a final diagnosis based solely on a blood sample.
When the CA 19-9 marker was added, sensitivity rose to 86.8 percent. Sensitivity means the test identified approximately 87 out of every 100 individuals who actually had early-stage pancreatic cancer.
However, this percentage does not mean the test provides a correct diagnosis for 87 percent of all individuals undergoing it, as the evaluation of any test also depends on its ability to exclude non-cases and its rate of false positives.
The test recorded false-positive results in 3.2 percent of low-risk individuals, and the rate rose to 15.6 percent among individuals in higher-risk groups. A false-positive result may lead to additional testing and health anxiety in a person who does not have a tumor.
The study also tested the assay in individuals with high-risk pancreatic cysts. Its sensitivity in detecting high-grade dysplasia, an advanced cellular change that may precede cancer development, was 64.3 percent.
In a small group of 19 individuals, RNA signature levels decreased during neoadjuvant chemotherapy and after tumor resection, then increased before disease recurrence in some cases.
