\A new study suggests that patients with prostate cancer who have low prostate antigen, or PSA, levels have a higher risk for cancer-specific death compared with patients whose PSA levels are high. A low PSA level was considered less than or equal to 2.5 ng/mL or 2.6 to 4 ng/m, while a high PSA level was considered 10.1 to 20 ng/mL The study was published online in the journal Cancer.

The researchers conducted the study in order to determine whether a very low PSA level was linked with greater prostate cancer-specific mortality among men with a Gleason score of 8 to 10. The researchers used the Surveillance, Epidemiology, and End Results program to identify 328,904 men with clinical T1 prostate cancer between the years 2004 and 2010. Additionally, a multivariate Fine-Gray competing risks regression analysis was used to determine prostate cancer-specific mortality as a function of the PSA level and Gleason score.

The researchers followed up with the patients at about 38 months. The findings identified that the adjusted hazard ratio for prostate cancer-specific mortality was 2.15 with a PSA level of less than or equal to 2.5 ng/mL, 1.60 with a PSA level of 2.6 to 4 ng/mL, 1.60 with a PSA level of 10.1 to 20 ng/mL, 2.08 with a PSA level of 20.1 to 40 ng/mL, and 3.23 with a PSA level greater than 40 ng/mL. The results suggest what is known as a U-shaped distribution. This means that there was a significant interaction between the PSA level and Gleason score such that only a PSA level less than or equal to 2.5 ng/mL significantly predicted poorer prostate cancer-specific mortality among patients with Gleason score of 8 to 10.

These findings are supportive of the fact suggestion that that low PSA levels in disease with a Gleason score of 8 to 10 may be a sign of aggressive and very poorly differentiated or anaplastic low PSA-producing tumors. The researchers say that those with low a PSA level and a Gleason score of 8 to 10 disease should be considered for clinical trials involving studying the use of chemotherapy and other novel agents for very high-risk prostate cancer.