CLINICAL RELEVANCE OF TRANS-RECTAL ULTRASOUND, BIOPSY, AND SERUM PROSTATE-SPECIFIC ANTIGEN FOLLOWING EXTERNAL-BEAM RADIOTHERAPY FOR CARCINOMA OF THE PROSTATE

Purpose: To correlate the results of routine transrectal ultrasound-guided prostate biopsies with the usual clinical parameters of digital rectal examination, prostate specific antigen and ultrasound in the follow-up of one hundred patients treated with radical radiotherapy for prostate cancer. Methods and Materials: Stage distribution of the 100 patients was T1b: 19, T2a: 24, T2b: 36, T3: 20, T4: 1. Median follow-up is 26 months (range 15-48). One hundred forty-one ultrasound-guided biopsies have been performed with four to seven specimens at each examination. Initial biopsy was scheduled 12 months after radiotherapy and repeated every 6 months until negative or until there was clinical or biochemical evidence of recurrence. Results: Negative biopsies were obtained at 12 months (range 9-15) in only 52%. Of 31 patients with a positive first biopsy who have had a second or third examination, 21 converted to negative at 16-29 months (median: 19) (stage T1b: 3, T2a: 6, T2b: 8, T3: 4). All 21 patients had maintained a normal or decreasing prostate specific antigen (PSA). At last review, negative biopsies had been obtained in 74% of patients: 79% (15/19) of T1b, 71% (17/24) of T2a, 72% (26/36) of T2b, and 76% (16/2 1) of T3/4. No patient with a negative biopsy has had a local recurrence. Transrectal ultrasound alone (sens: 49%, spec: 57%) was no better than rectal exam (sens: 73%, spec: 66%) in predicting a positive post radiotherapy biopsy. Metastatic disease developed in seven patients, 12% (3/26) of those with a positive biopsy and 5% (4/74) of those with a negative biopsy (p < 0.01). All seven presented first with a rising PSA. Conclusion: For patients with a positive biopsy 12 to 24 months after radiotherapy, PSA is the best indicator of biologically active tumor. This preliminary analysis indicates that there may be no need to treat patients with a positive biopsy and negative PSA in the absence of clinical recurrence.