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Biochemical failure after radiation therapy for prostate cancer: Racial differences.

e16071 Background: Many guidelines for prostate cancer treatment are based on clinical trials with predominantly white patient (pt) populations. The generalizability of these results assumes similar tumor biology among all races. We set out to examine biochemical failure (PSA failure) rates in a cohort of pts after definitive external beam radiation (EBRT) in the racially diverse population at our institution.


METHODS
We conducted an IRB-approved retrospective review of pts treated with definitive EBRT from January 2000 to April 2008. We excluded from analysis pts who received brachytherapy, salvage, adjuvant or palliative radiation. Race, country of origin, diagnostic data, pre- and post-treatment PSA, Gleason score (GS), clinical stage (CS), and treatment history were reviewed. CS was based on the original clinician's assessment at time of diagnosis. PSA failures were defined using 1996 ASTRO criteria. Two cohorts were grouped by race: white and nonwhite. Statistical analysis was performed using Fisher's Exact test.


RESULTS
One hundred seventy-four pts were treated with definitive EBRT. Forty-four pts were white and 130 were nonwhite. Both cohorts demonstrated similar distributions in GS and CS (see Table ). The white cohort had a high proportion of pts with a pretreatment PSA <10 ng/ml (66%) as compared to the nonwhite cohort (46%). Distribution of race/region of origin is: White 44 (25%), Black-American 78 (45%), Black-Caribbean 28 (16%), Black-African 2 (1%), Hispanic 21 (12%), Asian 1 (1%). Just under 50% of each group received neoadjuvant androgen deprivation therapy. PSA failure rate was 7% for the white cohort and 13% for nonwhite (p = 0.41).


CONCLUSIONS
In this retrospective analysis, there was no statistical difference among races with regard to PSA failure rates. The PSA and Gleason trends in each cohort were consistent with published data on this topic. Dedicated evaluation of the prognostic value of traditional risk stratification in nonwhite pt populations in a prospective trial is warranted. [Table: see text] No significant financial relationships to disclose.