Characteristics Of Baseline PSA And PSA Velocity In Young Men Without Prostate Cancer: Racial Differences

BackgoundAs a tumor marker, prostate specific antigen (PSA) is widely used in prostate cancer screening, and significantly increased the diagnosis of prostate cancer. No uniform international standard was set for PSA threshold in men age under 50. Some scholars have suggested reducing the threshold of PSA level for early detection and diagnosis of prostate cancer, which aimed to improve quality of life and prolong life expectancy. There are three main reasons for reducing the threshold of PSA in male age under 50. First, the age adjusted mortality rate for prostate cancer per 100,000 males between ages 55 and 64 is 18. Since death from prostate cancer occurs, on average, 15 to 20 years after diagnosis of an early cancer, men dying at age 55 to 64 likely could have been cured by diagnosis and effective treatment prior to age 50.Second, clinically limited curable cancer could be detected more easily by using PSA for screening in younger male. Finally, as young male is less likely to have serious underlying diseases, more direct treatments, such as surgery, could be selected. The incidence rate of prostate cancer in male age under 50 was 0.8% -1%, with variation between different ethnics. Prognosis could be improved by early diagnosis of prostate cancer. Some studies showed that measurement of the first PSA (baseline PSA) could predict the risk of prostate cancer. Rate of change in prostate specific antigen (prostate specific antigen velocity, PSAV) has been well proven to be capable of offering systematic assessment on the risk of prostate cancer. Combination of PSAV and PSA can guided prostate biopsy, and improve the sensitivity and specificity of diagnosing prostate cancer. To our knowledge no prior published comparison data with regard to the characteristics of PSA and PSA velocity among young Chinese, African American (AA), and Caucasian American (CA) men in the literature. ObjectiveTo investigate the distributions and characteristics of baseline PSA and PSA velocity in Chinese, AA,CA men 50 years old and younger without prostate cancer.Subjects and MethodsPSA database was selected from the Department of Urology, Guangzhou No. 1 People's Hospital between January 2002 and October 2009 in males who aged less than 50 and underwent the first measurement. Serum PSA was also analyzed in African American (black) and American Caucasian (white) males who aged≤50 and underwent the first measurement, with the database originated from The Institute of Prostate Center, Duke University from January 2000 and March 2009. Inclusion criteria were (1) young male aged less than 50, and (2) without prostate cancer and prostate sarcoma. Baseline PSA and PSA velocity Chinese were analyzed in African American (AA), and American Caucasian (AC) men aged≤50 without prostate cancer. The three race groups were divide into <30 years of age group ,31-39 and 40-50 age group, baseline PSA and PSAV among different age groups of different races were compared, and racial differences in PSA and PSAV were also assessed. The differences of baseline PSA and PSA velocity between races were assessed. The important cutoffs of baseline PSA and PSA velocity were used to stratify patients among races.Results4,206 Chinese, 997 AA, and 2,030 AC were included. The rates of baseline PSA of≥1.0,≥2.5, and≥4.0 ng/ml was 24.4%, 4.2%, and 2.1% in Chinese, 30.7%, 5.2%, and1.8% in AA, 29.7%, 5.3%, and 2.8% in CA, respectively. The rates of PSA velocity of≥0.35,≥0.75, and≥1.0 ng/ml/year was 6.0%, 3.1%, and 2.6% in Chinese, 5.3%,2.3%, and 1.7% in AA, 5.4%, 3.5%, and 3.3% in CA, respectively. The mean and median PSA of Chinese young male, African-American young male and American Caucasian young male were 1.0 ng / ml, 0.649 ng / ml; 1.0 ng / ml, 0.7 ng / ml; 1.2 ng / ml, 0.7 ng / ml,respectively. The mean and median PSAV of Chinese young male, African-American young male and American Caucasian young male were 0.196 ng / mL / y, 0.028 ng / mL / y; 0.105 ng / mL / y, 0.01 ng / mL / y; 1.283 ng / mL / y, 0,respectively. African American youth have a lower baseline PSA and higher PSAV compared with American Caucasian and Chinese young male. No statistical difference (P = 0.707) was found in baseline PSA and PSAV between African-American young male and American Caucasian young male. The baseline PSA in American Caucasians was correlated with PSAV (P <0.01), and no significant correlation (P = 0.897) was found between PSA and PSAV in Chinese young male. No significant correlation ( P = 0.608) between baseline PSA and PSAV was also found in black young male. PSA was <2ng/ml in over 90% of young male without prostate cancer among the three races. PSAV was <0.30ng/ml/y in over 92% of young male without prostate cancer among the three races.ConclusionsThe distribution of baseline PSA and PSA velocity in young male among Chinese, AA, and CA races is different. African American young males have a lower baseline PSA and higher PSAV compared with American Caucasian adults and young males as well as Chinese young males. These characteristics should be taken into account when using these variables to stratify risk of prostate cancer in young males.