Statins may improve OS in advanced PCa patients

Statin use by patients with advanced prostate cancer who are being treated with androgen deprivation therapy (ADT) may improve overall survival (OS) and prostate cancer-specific survival, according to an examination of the national Veterans Administration (VA) database.

Among men who were on ADT for longer than 6 months, median OS was 6.5 years in those taking statins compared with 3.95 years in men who weren’t taking statins (p<.0001), reported Natasza Posielski, MD, at the AUA annual meeting.

Evidence has been accumulating that statins may be beneficial in men with prostate cancer. Recently, data from a nationwide registry study from Denmark (n=31,790) showed that statin use after a diagnosis of prostate cancer was associated with an adjusted hazard ratio (HR) of 0.83 for prostate cancer mortality and 0.81 for all-cause mortality, both of which were significant.

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Castrate-resistant prostate cancer may signal the development of a de novo pathway for testosterone production within tumor cells. One hypothesis is that by decreasing cholesterol synthesis, which is a precursor for testosterone, this new pathway of testosterone production can potentially be inhibited, thereby delaying progression of prostate cancer.

Recent trials showing the benefits of medications such as abiraterone acetate (ZYTIGA) and docetaxel (Taxotere) in combination with ADT suggest that combination therapy may act synergistically to improve the ability of ADT to prolong survival, said Dr. Posielski, of the University of Wisconsin Hospitals, Madison, working with Kyle A. Richards, MD, and colleagues.

Patients on ADT represent a novel group to study.

“The initiation of ADT may be this therapeutic niche where cells are developing altered signaling where there may be an increased benefit of adding other therapies. Hence, we wanted to study the role of statins in this setting,”Dr. Posielski said. In addition, statins have a favorable side effect profile and are available generically.

Next:How the study was conductedFrom the VA database, researchers identified 87,346 men diagnosed with prostate cancer between 2000 and 2008 and who were treated with ADT for at least 6 months. Of these, 53,360 used statins and 33,986 did not.

Statin users had a median age of 73 years compared with 76 years for those who didn’t use statins (p<.001). Statin users were also more likely to have Charlson Comorbidity Index >3 (3.1% vs. 2.5%, p<.001) and more likely to have a high-grade (Gleason score 8 to 10) cancer (12.3% vs. 10.9%, p<.001).

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With follow-up through May 2016, statin users not only had significantly longer OS (HR: 0.69) but also a decreased rate of death from prostate cancer (9.0% vs. 12.7%, p<.001). Statin use was also associated with a longer time to a skeletal-related event (median: 5.9 vs. 3.7 years, p<.001).

The differences in OS and prostate cancer-specific survival were surprising given that statin users had higher grade cancers and a higher Charlson comorbidity index, Dr. Posielski said. A major limitation of the study is that Gleason score data were missing for about 70% of the cohort.

Although an association between statin use and improved OS and prostate cancer-specific survival shows up in several observational studies, “I think it’s too early in the process for this to be a protocol to prescribe statins for all patients,” Dr. Posielski said. “It will require further study.”

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