Histological characteristics and clinical significance of Japanese prostate cancer with low levels of prostate specific antigen of 4.0 ng/ml or lower]

They set a normal limit of prostate specific antigen (PSA) to 4.0 ng/ml in Tandem R assay at most institutions. We investigated clinical and histological characteristics of prostate cancer based on whole mount step-section histology of radical prostatectomy specimens, and taking notice of Japanese prostate cancer whose levels of PSA are less than 4.0 ng/ml in normal levels.One hundred and twenty-two patients underwent radical prostatectomy for clinically resectable prostate cancer at University Hospital from February 1992 to April 1997. Clinicopathological findings were stratified according to the preoperative PSA levels in 111 patients without preoperative endocrine therapy. Immunohistochemical study for PSA was conducted in 7 randomly selected patients.Of the patients 22 (19.8%) had normal (4.0 ng/ml or lower) preoperative serum PSA. Mean tumor volume in this PSA range was 1.5 cm3 with one pT 0 case included. Pathologically organ confined, potentially curable disease (< pT 3) was found in 17 (77.3%) patients and extracapsular extension and seminal vesicle invasion in 5 (23.8%), respectively. No patients had positive pelvic lymph nodes. Well differentiated tumors of Gleason scores 2-4 were found in 9 (40.9%) of the patients, moderately differentiated tumors (Gleason scores 5, 6) in 5 (22.7%) and poorly differentiated histology (Gleason scores 7-10) in 7 (31.8%). Sixteen (72.7%) patients had clinically significant tumors (> 0.5 cm3, Gleason score > or = 7). All 7 patients had positive staining for PSA, but its intensity did not correlate with serum PSA levels.Many prostate cancers found in surgical specimens were clinically significant despite the low levels of PSA and potentially curable by definitive treatment. Age, co-morbidity and other clinicopathological variables as well as PSA levels should all be taken into account when treatment options are discussed.