Evaluation of resistance index in patients with prostate cancer

Background: The purpose of this study was to evaluate the relationship of the resistance index (RI) of the prostate measured by transrectal ultrasonography (TRUS) in Taiwanese prostate cancer patients to Gleason score, staging and prostate volume. Patients and Methods: Forty-five patients (mean age, 73.3 years; range 56 to 97) diagnosed to have prostate cancer via prostate biopsy and/or transurethral prostatectomy were recruited for our study. The patients were divided into 3 groups according to Gleason score, low grade (2-4, LG n=14), intermediate grade (5-7, IG n=14) and high grade (8-10, HG n=17) groups. The blood flow pattern and mean RI of the prostate vessels were recorded and compared with age, prostate volume, serum prostate specific antigen (PSA) and oncological stage. A follow-up color Doppler ultrasonography was also performed in 17 patients after 3-6 months of hormone therapy and the changes of RI were recorded. Results: The mean age, serum PSA and prostate volume were comparative among the three groups, but the differences of RI were statistically significant (p=0.029). Advanced prostate cancer (HG group) tended to have higher RI. There was a close correlation between RI and Gleason score (Spearman R=0.452, p=0.002). The high RI phenomenon could be reversed after 3-6 months of hormone therapy (paired t-test, p<0.05). Conclusion: High grade prostate cancer tends to have higher RI. RI measurement during color Doppler TRUS may be helpful in the evaluation of the vascularity of prostate cancer and its vascular changes to hormone treatment.