The significance of needle biopsy after irradiation for stage C adenocarcinoma of the prostate.

The presence of malignant cells in needle biopsy specimens following irradiation for adenocarcinoma of the prostate has been used to criticize or defend this treatment. At Walter Reed Medical Center, 38 consecutive patients with Stage Cadenocarcinoma underwent definitive irradiation between August 1970 and March 1973. The median dose to the pelvis was 7000 rads in 31 fractions in 43 days (2030 ret). Post treatment examination included palpation of the prostate and transperineal biopsy of the most suspicious areas. Gradual disappearance of the palpable tumor occurred in all patients. Two men have had clinical evidence of re-growth of prostatic cancer. Thirty-three patients have had up to seven biopsies each for a total of 139, an average of four biopsies per patient. There were 49 positive and 90 negative biopsies. Positive biopsy rate correlated only with the interval after irradiation--60% at six months, 37% at one year, 30% at 18 months, and approximately 19% after two and one-half years. There was no correlation of biopsy results with pre-irradiation estrogen or orchiectomy, with time-dose-fractionation relationships, or with prognosis. These biopsies provide interesting data about the regression rate of prostatic adenocarcinoma, but they have no significance for the individual patient. They have, therefore, been eliminated from follow-up studies.