Statin effect in prostate cancer may be caused by reduced inflammation

SAN FRANCISCO – Long-term use of statins may protect against lethal forms of prostate cancer by altering the inflammatory profile of the tumor microenvironment, according to the results of a new genetic analysis of prostate cancers in men in the Health Professionals Follow Up Study.

A previous analysis from the Health Professionals Follow Up Study published in 2015 showed no difference in the risk of lethal prostate cancer for those who began using statins after diagnosis of their tumors.

^{Jim Kling/MDedge News}

Dr. Emma Allott

A genetic analysis of these lethal cases revealed that patients taking long-term statins had a lower incidence of phosphatase and tensin homolog (PTEN)–null cancers, which are associated with worse outcomes. Integrating molecular and epidemiologic data, PTEN and PI3K (phosphatidylinositol) signaling and inflammation and immune activation appear to be two potential mechanisms contributing to this association.

Genetic analysis of normal prostate tissue also showed unique traits among statin users. “We found that the top ten pathways that came up were almost all involved in inflammation or immune activation, and we found those differences only in tumor and adjacent normal prostate tissue. We didn’t see any pathways that were differentially expressed by statin use within the tumor tissue itself,” said Emma Allott, PhD, who presented the research at a poster session at the annual meeting of the American Urological Association.

An association between statin use and improved survival was first described in a 2006 study based on results from the Health Professionals Follow Up Study. Since then, “we’ve been generating molecular data on cancers that developed in statin users and nonusers,” said Dr. Allott of the University of North Carolina, Chapel Hill.

Of the 5,792 prostate cancer diagnoses, 17% were advanced cases, defined as stage T3b or more, having spread to lymph nodes or metastasized, or lethal; 13% were lethal, 46% were positive for the ERG oncogene, and 14% were PTEN-null. “Statin use was associated with a lower risk of PTEN-null prostate cancer, so that seems to drive some of the reduced association with lethal disease,” said Dr. Allott.