Disparity in genomic application?
The Decipher genomic classifier (GC) can aid in clinical decision
making, due to its high expected performance. However, African American
men (AAM) are underrepresented in most studies evaluating CG, so we do
not have sufficient data in this population46.
Several studies have sought to investigate this aspect, recruiting a
greater number of AAM patients. They demonstrate that the biological
characteristics of prostate tumors are substantially different in AAM
compared to EAM, and further suggest that AAM patients are associated
with a higher risk of aggressive disease and have higher decipher than
non-African-American men46 4748. This findings prompt for a careful monitor of AAM
patients post radiotherapy prostatectomy. The studies also suggest that
GC is a stronger predictor in AAM than in EAM4647. One study investigated the variation in the
distribution and prognostic value of molecularly defined PCa
transcriptomic subtype classifiers by race using Decipher. Five
classifiers that identify prostate tumor subtypes were studied and found
that the subtypes differed in frequency between AAM and EAM. The
association between subtypes and a genomic risk score differed by race,
suggests that some subtypes may have differential prognostic value
between racial groups, independent of tumor
clinicopathology.49 Another prospective study was
conducted to determine the genomic risk of reclassification (GrR)
between conventional clinical risk classifiers and the Decipher score,
using a clinically balanced cohort of African-American men and
non-African-American men. This study found that the majority of AAM men
had a higher Decipher score than EAM patients, thus AAM were twice as
likely to experience genomic risk of
reclassification50. Additionally, in a
multi-institutional retrospective analysis of 1,152 patients (596 AAM
and 556 EAM), Decipher score was compared with Gleason grade (GG) groups
and a positive relationship was found between these two parameters such
that a higher Gleason grade is associated with a higher Decipher score48. The study also found that AAM has a higher
Decipher scores only in lower GG group (GG1/2). However, the average
genomic-risk score (average of 19 signatures excluding Decipher) is
significantly lower in AAM when compared to EAM with high GG group (GG
4/5) group. This findings imply that racial disparity existed might be
more profound in the lowest and highest GG group48.
These differences in the tumor biology between AAM and EAM may provide
an explanation for the racial disparities in prostate cancer.