What is the optimal timing for a prostate biopsy following radiation therapy?

Updated: Dec 30, 2020
  • Author: Kenneth A Iczkowski, MD; Chief Editor: Liang Cheng, MD  more...
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Answer

Answer

The recommended timing of a prostate biopsy after irradiation is a minimum of 1 year after completion of radiation therapy. This approach reliably discloses residual cancer. [25] Biopsy samples should be taken from as many sites as possible.

Crook et al reported that ultrasonographically guided biopsies beginning 12 months after radiation therapy revealed failure in 103 (21%) of 479 of patients; however, in 67 of these patients, biopsy results converted to negative after a mean of 28 months. [26] Thus, the tumor may take up to 28 months to resolve.

In a study of 160 patients, at a median 6.7-year follow-up, 21% of patients had a positive biopsy result. [27] The radiation therapy failure rate has been found to be 25-90%, depending on whether failure is based on biochemical or biopsy evidence. Notably, in a study by Miller et al, 17% of patients with positive biopsy findings remained clinically free of disease at more than 10 years of follow-up. [28] It has also been reported that in patients undergoing salvage radical prostatectomy after failure, recurrence was detected by biopsy after a mean of 3.5 (0.5-17) years.

A study by Marinelli et al found that in patients with stage II prostate cancer, 95% of postradiation biopsy specimens were negative for cancer; this figure was 55% for stage III cancer. [29]

In a study by Cheng et al, salvage prostatectomy after radiation failure produced a 5-year, cancer-specific survival rate of 91%; 83% of patients were free of metastases. [30]

Findings from Radiation Therapy Oncology Group (RTOG) study 94-08 comprising data from 831 men who underwent postradiation therapy (n = 398 radiation alone; n = 422 radiation + total androgen suppression) for localized prostate cancer revealed postive postradiation biopsy was associated with higher rates of biochemical failure, distant metastases, and inferior overall survival in those with high-grade tumors (Gleason score ≥7). [31]


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