Relationship of ultrasound staging and bilateral biopsy positivity to outcome in stage T1c prostate cancer treated with radiotherapy.

OBJECTIVES

The strict definition of Stage T1c prostate cancer is that the tumor is not palpable on digital rectal examination (DRE) or seen on imaging studies such as ultrasound. The inclusion of ultrasound imaging was brought about without an understanding of the relationship between ultrasound upstaging and prognosis. We have also noticed that in clinical practice, treatment decisions are made on the basis of the finding of bilateral versus unilateral biopsy positivity. The objectives in this study were to determine the prognostic significance of upstaging by transrectal ultrasound (TRUS) to uT2 or uT3, and unilateral versus bilateral biopsy positivity in patients with Stage T1c cancer as determined by DRE (DRE-Stage T1c patients).

METHODS

Between 1987 and 1995 there were 643 patients with DRE-Stage T1-T2 prostate cancer treated with external beam radiotherapy; 24 had T1a, 76 had T1b, 183 had T1c, 133 had T2a, 168 had T2b, and 59 had T2c. Of these, 135 DRE-Stage T1c patients underwent ultrasound staging and 122 underwent bilateral prostate biopsies. All had pretreatment prostate-specific antigen values (PSAs) available and no patient received adjuvant androgen ablation. The median pretreatment PSA was 9.1 ng/mL, median radiotherapy dose was 66.0 Gy, and median follow-up was 41 months. Post-treatment failure was defined as disease recurrence and/or two elevations in PSA on consecutive follow-up visits.

RESULTS

The 5-year freedom from failure rate for DRE-Stage T1c patients (71%) was not significantly different from that of DRE-Stage T1b (65%) or DRE-Stage T2a (71%) patients. There was a trend (P = 0.1) toward a worse outcome for DRE-Stage T2b/T2c patients compared with DRE-Stage T1b/T1c/T2a patients. The distribution of DRE-Stage T1c patients by ultrasound staging was 29 with uT1c, 88 with uT2, and 18 with uT3 findings. Twenty percent of patients had bilateral positive biopsy specimens. In univariate and multivariate analyses, the only correlates of patient outcome were pretreatment PSA (P < or = 0.002) and isocenter dose (P = 0.03). TRUS upstaging had no effect on freedom from failure; uT1c patients had about the same risk of relapse or a rising PSA as uT2 or uT3 patients. Patients with bilateral positive prostate biopsy specimens had about the same prognosis as those with unilateral positive biopsy specimens.

CONCLUSIONS

For patients with DRE-Stage T1c prostate cancer, the data indicate that ultrasound staging and bilateral biopsy positivity are not predictive of outcome for patients treated with external beam radiotherapy and treatment decisions should not be based on these parameters.