Luminal and basal subtyping of prostate cancer may provide a clinical tool for predicting which patients will benefit from androgen deprivation therapy (ADT) after prostatectomy, according to a report published in JAMA Oncology (published online May 11, 2017; doi:10.1001/jamaoncol.2017.0751).
The lineage of prostate cancer is unknown and there is a need for a molecular subtyping approach to identify distinct subgroups that will benefit from ADT treatment. Luminal and basal cells have been found to include lineages that may lead to prostate cancer, which has prompted research efforts to characterize luminal and basal cells that share characteristics similar to those of stem cells. However, this research is ongoing and the similarities and differences of luminal and basal lineage prostate cancer remain unresolved.
Shuang G Zhao, MD, department of radiation oncology, University of Michigan, and colleagues conducted a study to identify prostate cancer subtypes based on luminal and basal lineage that may harbor associations with clinical outcomes and response to ADT treatment. Researchers used the PAM50 classifier to subtype 1567 retrospective and 2215 prospective prostate cancer samples into 3 subtypes: luminal A (retrospective, 538 [34.3%]; prospective, 737 [33.3%]), luminal B (retrospective, 447 [28.5%]; prospective, 723 [32.6%]), and basal (retrospective, 582 [37.1%]; prospective, 755 [34.1%]). Primary outcomes measured were metastasis, biochemical recurrence, overall survival (OS), prostate cancer-specific survival (PCSS), associations with biological pathways, and clinicopathologic variables.
The retrospective cohort yielded the poorest clinical prognoses in luminal B subtype (10-year biochemical recurrence-free survival [bRFS], 29%; distant metastasis-free survival [DMFS], 53%; PCSS, 78%; OS, 69%), followed by basal prostate cancers (10-year bRFS, 39%; DMFS, 73%; PCSS, 86%; OS, 80%) and luminal A prostate cancers (10-year bRFS, 41%; DMFS, 73%; PCSS, 89%; OS, 82%). However, luminal B subtype demonstrated significantly better response to postoperative ADT compared with luminal A or basal subtype.
After finding that luminal and basal subtypes of prostate cancer show divergent clinical behavior, researchers concluded that these subtypes indicate a biomarker for predicting which patients may benefit most from ADT treatment after prostatectomy. This finding, they wrote, could provide a “potential clinical tool to personalize ADT treatment.” — Zachary Bessette
