Scientists in the UK say testing for a tumor suppressor protein called p16 can improve diagnostic accuracy for mesothelioma. It may also help predict which patients are likely to have the best treatment response.
The p16 protein is encoded by the CDKN2A gene. Many people with mesothelioma are missing this gene.
Previous studies show a lack of p16 may be linked to lower cancer survival. Now, researchers in Manchester say it should be added to routine tests to improve prognostic and diagnostic accuracy for mesothelioma.
The Challenge of Diagnostic Accuracy for Mesothelioma
It is not easy to diagnose mesothelioma. There is no single test that can show if a person has this cancer. Diagnosis usually involves blood tests, imaging studies, and a biopsy. Doctors also need to know if a person has been exposed to asbestos. Asbestos is the main cause of mesothelioma.
The more tests a person has, the longer it takes to get an accurate diagnosis. Even with all of the current tests, the diagnosis can still be wrong. It is easy to mistake mesothelioma for other conditions. In the meantime, a mesothelioma tumor may be growing quickly.
Anything that can improve diagnostic accuracy for mesothelioma is also likely to improve survival.
How Does p16 Level Impact Mesothelioma?
P16 plays an important role in regulating the life cycle of cells. It slows down the progression from the protein-making phase to the DNA replicating phase. Mesothelioma can occur when DNA does not replicate properly. P16 helps keep that from happening by forcing cells to slow down.
The new study took place at Wythenshawe Hospital at Manchester University. The hospital uses an advanced test called fluorescence in situ hybridization (FISH) to test for p16 deletion.
Researchers analyzed p16 FISH tests from 216 mesothelioma patients. They wanted to evaluate the test’s diagnostic accuracy for mesothelioma. They also hoped to see how it relates to mesothelioma progression and survival.
Sixty percent of the mesothelioma samples were missing p16. Even more important, there were no false positive results. P16 deletion was only found in people with mesothelioma. The patients who were missing p16 had a much shorter survival than other mesothelioma patients (285 days versus 339 days).
The researchers conclude that p16 FISH testing can improve diagnostic accuracy for mesothelioma. Their results mirror what previous p16 studies have also found.
“In this study, 60% of mesotheliomas harbour a homozygous deletion of CDKN2A and can be accurately, reliably and efficiently identified by p16 FISH testing,” writes lead author Kelly Marshall. “This test can be embedded within routine practice in mesothelioma pathways to enhance diagnostic accuracy.”
P16 deletion or mutation is linked to poor survival in melanoma and cervical cancer, too.
Marshall, K, et al, “Homozygous deletion of CDKN2A in malignant mesothelioma: Diagnostic utility, patient characteristics and survival in a UK mesothelioma centre”, November 5, 2020, Lung Cancer, https://www.lungcancerjournal.info/article/S0169-5002(20)30673-5/fulltext