Predictive Value of Prostate-Specific Antigen Density on Tumour Grade in Diagnosis of Prostate Cancer: A Hospital-Based Cross-Sectional Study

Abstract

Background: Prostate cancer is the most common urologic malignancy in men, it is witnessing a huge burden in developing countries. Prostate-specific antigen has served as a tool in diagnosis and prognostication. To improve its sensitivity, Prostate-specific antigen density is being used to discriminate between benign and malignant conditions to avoid the incidence of unnecessary biopsy. Similarly, it is important to establish the importance of Prostate-specific antigen density in prognostication to help in treatment stratification. The aim of this study, therefore, is to assess the relationship between Prostate-specific antigen density and tumour grade using the Gleason score.

Methodology: This study was a prospective cross-sectional study carried out between 2015-2016. It involved 191 consecutive patients who were either asymptomatic or symptomatic with elevated prostate-specific antigen (PSA)/abnormal digital rectal examination findings or both. They had a Prostate volume assessment and digitally guided prostate biopsy. Prostate-specific antigen density was calculated, and histopathology reports were evaluated. Data were analysed using SPSS version 20.0. Pearson correlation coefficient and test of ANOVA were used to assess the relationship between prostate-specific- antigen and Gleason score while a scatterplot was used to determine the relationship between prostate-specific antigen and prostate volume. The level of significance was set at p< 0.05.

Results: All patients in this study were Nigerians, mean age of the study population was 68.2+ 9.4 years. The median PSA for patients with prostate cancer was 76.9ng/ml and 14.5ng/ml for patients with benign disease, the difference was statistically significant (p<0.001), and median prostate volume was 84.5mls while the median PSAD was 0.25. PSAD for Gleason score 2-4,5-7,8-10 was 0.4,0.8 and1.1 respectively which was statistically significant using a test of ANOVA (p=0.001). Pearson correlation coefficient revealed a statistically significant correlation between Prostate-specific antigen and Gleason score (r= 0.375, p=0.024). Using Fisher's exact test there was a statistically significant difference between PSAD for benign prostatic disease and carcinoma of the prostate, p<0.001.

Conclusion: The study revealed that Prostate-specific antigen density has a statistically significant predictive value for tumour grade using Gleason score, however no statistically significant correlation was observed between prostate-specific antigen and prostate volume in prostate cancer.

Keywords: Gleason Score; PSAD; Prostate Cancer; Tumour Grade.

Figure 1:

Prostate volume (mls) Correlation between Prostate volume (mls) and total PSA (ng/ml) (Scatter plot) Range of prostate volume for benign prostatic disease (40-370) mls, mean prostate volume (98±55.53). Range of prostate volume for CaP (27-320) mls, mean prostate volume (92.61±63.69), P=0.536

Figure 2:

PSA density and Gleason score, r=0.375, p=0.024