Risk allele for advanced stage prostate cancer found in African–American men
MedWire News: The presence of the Broad11934905 AG allele on chromosome 8q24 in African–American men indicates an increased risk for non-organ confined high stage prostate cancer, and a trend towards early biochemical recurrence after surgery, study findings show.
This single-nucleotide polymorphism (SNP) is only found in people of African ancestry, and may help to explain some of the disparities observed in African–American men with prostate cancer compared with men of other origins, say the researchers.
“African–American men have the highest incidence and mortality from prostate cancer in the world and have worse prognosis when compared with Caucasian Americans,” explain Matthew Freedman, from Harvard Medical School in Boston, Massachusetts, USA, and colleagues.
A cohort of 106 African–American men treated with radical prostatectomy (RP) for prostate cancer were genotyped for six SNPs on three regions of chromosome 8q24. Previous research has associated an inherited variation of one region of chromosome 8q24 with an increased risk for prostate cancer.
The researchers examined any detected SNPs for links with clinicopathologic data, including stage and grade at prostatectomy, age at diagnosis, and incidence of biochemical recurrence after treatment.
In all, 38.2% of patients had high stage cancer (T3-4) and 24.8% experienced biochemical recurrence after RP, defined as at least one prostate-specific antigen (PSA) measurement of more than 0.2 ng/ml during follow-up. The mean follow-up time was 49.1 months.
The Broad11934905 risk allele was the only SNP to show a significant association with high stage disease. Multivariate analysis adjusted first for age, and separately for PSA levels, showed that patients with this SNP had a 3.3- and 3.5-fold increased risk for a high T stage, respectively, compared with men without it.
Possessing the Broad risk allele was also associated with a 1.813 times higher chance of biochemical recurrence, however this was not a statistically significant finding.
“Understanding how or if polymorphisms have differential impacts across populations remains an important and unanswered question and has important implications for delivering personalized medicine,” write Freedman et al in the journal Cancer Epidemiology Biomarkers and Prevention.
The team acknowledges that exactly how this SNP is related to prostate cancer aggressiveness is unknown since it is located in a region of chromosome 8q24 with no known genes.
They conclude: “Further study… is warranted because [studies on SNPs] show promise as possible markers of aggressive disease.”
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By Sarah Guy