Transrectal ultrasonically-guided core biopsies in the assessment of local cure of prostatic cancer after radical external beam radiotherapy.

Fifty-five patients were included in an extended follow-up after radical radiation therapy (RRT) for localized prostatic cancer (T1-3, Nx, M0). Local cure was assessed by a combination of digital rectal examination (DRE), transrectal ultrasound (TRUS) and systematic 'mapping' with TRUS-guided core biopsies (TGCB). After a mean follow-up of 6.8 years, 33% (18/55) of the patients were locally free of tumour, while in 67% (37/55) of cases residual cancer was demonstrated in the biopsies. Endocrine treatment did not influence the local cure rate, nor did the T stage of tumour grade at diagnosis or the cumulative radiation effect (CRE) values within the range of the present study. The sensitivity of DRE and TRUS was low; 37% and 20% respectively, while the specificity of the DRE and TRUS methods was 83% and 94% respectively. The conclusion of the study is that residual tumour was found in the high proportion of biopsied patients nearly 7 years after RRT and that multiple, TRUS-guided core biopsies are mandatory in the assessment of local cure in patients irradiated for prostatic cancer; both DRE and TRUS on their own are less reliable.