The relationship between prostate-specific antigen and TNM classification or Gleason score in prostate cancer patients with low prostate-specific antigen levels.

BACKGROUND: Prostate-specific antigen (PSA) is a useful biomarker for risk classification in patients with prostate cancer. However, it is unclear whether a correlation exists between low PSA levels (<10 ng/ml) at diagnosis and prognosis. METHODS: Of the 642 Japanese patients who underwent prostate biopsy and were diagnosed with prostate cancer at Kanazawa University Hospital from 2000 to 2010, 406 patients with a PSA level <20 ng/ml were retrospectively reviewed. RESULTS: PSA levels in 275 (68%) patients were <10 ng/ml. Although the percentage of Gleason score 8-10 in patients with a PSA level of <3.5 ng/ml was higher than that in patients with a PSA level between 3.5 and 10 ng/ml, it was not statistically significant. On the other hand, the percentage of higher stage (T3 and T4) patients with a PSA level <3.5 ng/ml was significantly greater than that in patients with a PSA level between 3.5 and 10 ng/ml (P < 0.0001). The percentage of metastases (N1 and M1) in patients with a PSA level <3.5 ng/ml was also significantly higher than that in patients with a PSA level between 3.5 and 10 ng/ml (P = 0.0112). CONCLUSIONS: Patients with prostate cancer with a PSA level <3.5 ng/ml at diagnosis had a more advanced stage of cancer compared with those with a PSA level between 3.5 and 10 ng/ml. Therefore, risk classification using PSA levels at diagnosis may need to take into consideration this specific PSA range in order to better predict survival.