Value of sextant biopsies in the assessment of local cure following external beam radiotherapy of prostatic adenocarcinoma

Between 1982 and 1992, 73 patients received radical external beam radiotherapy (EBR) for prostatic adenocarcinoma at the Central Hospital, Västerås, with an average dose of 68.1 Gy (range 64.5-72.5 Gy) and an average cumulative radiation effect (CRE) of 18.2 (range 17.1-19.9) All patients had a negative bone scan prior to treatment and presented with clinical stage T1-T4,Nx,Mo. Twenty-four out of 36 surviving patients consented to participate in a follow-up study which included transrectal, ultrasonically guided prostate biopsies. The average follow-up from EBR to biopsy was 5.5 years (range 3.6-11.1 years). Sixteen (67%) of the patients had a positive biopsy. The average PSA level in the biopsy-positive group was 35.7 ng/mL (range 3.9-200 ng/mL). In the biopsy-negative group, the average PSA was 3.7 ng/mL (range 0.2-13.0 ng/mL). The conclusion is that the degree of local cure achieved in patients with prostatic cancer treated with external beam radiotherapy is low (33%), and that a higher radiation dose may be required to eradicate this malignancy.