[1047] Differences in Prostate Cancer Grade, Stage, and Location in Radical Prostatectomy Specimens from United States and Japan

Hiroyuki Takahashi, Jonathan I Epstein, Shin Wakui, Toshihiro Yamamoto, Bungo Furusato, Miao Zhang. Jikei University School of Medicine, Tokyo, Japan; Johns Hopkins Hospital, Baltimore, MD

Background: Although it is recognized that prostate cancer is different in Japanese and North American men, there have been few histological studies comparing prostate cancer at radical prostatectomy between the two groups in the modern era.
Design: 373 consecutive totally embedded RP cases (162 US; 211 Japan) from 2012 were reviewed. In addition to routine parameters, tumor location (peripheral zone vs. transition zone) and tumor volume was recorded. Tumor volume was calculated by 4/3Πx(L/2)x(W/2)x(H/2) which is the measurement of a scalene ellipsoid.
Results: United States men were significantly younger (mean age 58.7y) than Japanese (mean age 64.6y) (p< 0.00001). Japanese tumors were characterized by: higher grade; larger volume; more advanced stage; increased lymphovascular invasion; and more likely to originate in the transition zone. In multivariate analysis, independent predictors of high tumor volume were Gleason grade and country of origin (Japan).

Radical Prostatectomy FindingsUnited StatesJapanp-value
Gleason Score 3+3=641.4%12.3% 
Gleason Score 3+4=736.4%47.4% 
Gleason Score 4+3=712.4%19.4% 
Gleason Score 4+4=84.9%4.3%Overall Grade Difference
Gleason Score 9 or 104.9%16.6%<0.00001
pT3a: Extra-prostatic Extension/SV &LN Negative25.3%50%<0.00001
pT3b: Seminal Vesicle Invasion &LN Negative3.3%10%<0.00001
Lymph Node (LN) Metastases1.3%7.4%<0.00001
Lymphovascular Invasion4.5%31.2%<0.00001
Tumor Volume1.1cm34.7cm3<0.00001
Soley TZ Location0.6%41.8%<0.00001

Conclusions: A major factor accounting for the larger, higher stage and grade tumors in Japanese is the lower prevalence of screening for prostate cancer in Japan. Whereas early, small, asymptomatic lower grade cancers are detected in the United States with screening, some Japanese cancers are only diagnosed when they are detectable on rectal examination or when symptomatic. Another contributing factor for the larger more advanced stage tumors in Japan may be explained by their location in the transition zone, where they are not palpable until advanced. Furthermore, these more anterior tumors are difficult to sample on needle biopsy possibly leading to a delay in diagnosis. The finding of a difference in zonality of prostate cancer between United States and Japanese cases is novel and may reflect differences in biology rather than different health care practice between the groups. If this data is confirmed, consideration should be given to encorporate transition zone sampling as part of routine needle biopsies in Japanese men.
Category: Genitourinary (including renal tumors)

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 184, Tuesday Afternoon


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