Is the Roach formula predictive for biochemical outcome in prostate cancer patients with minimal residual disease undergoing local radiotherapy after radical prostatectomy?

Abstract 

Purpose

To find out if the risk of biochemical failure can be predicted applying the risk assessment for lymph-node metastases as suggested by the Roach formula for patients with minimal residual disease after radical prostatectomy undergoing adjuvant radiotherapy.

Materials and methods

Patients after radical prostatectomy presenting with pT3-tumours or positive surgical margins, negative nodes and with a post-operative and pre-radiotherapy PSA level ⩽0.1ng/ml and without hormonal therapy were selected. Patients had received local 3D-conformal radiotherapy in the prostatic region with 66–72Gy. According to the risk stratification of the Roach formula patients were divided into two groups: Group 1 with probability of positive lymph-nodes <15% and Group 2 with ⩾15%. Biochemical recurrence was defined by reaching a PSA level ⩾0.2ng/ml.

Results

A total of 55/288 patients could be identified, 26 patients in Group 1 and 29 patients in Group 2. Mean follow-up was 45months. Biochemical recurrence free survival after 5years was 78% for all patients and showed a significant difference between Group 1 (100%) and Group 2 with (58%; p=0.004).

Conclusion

The risk for biochemical failure after adjuvant radiotherapy in post-operative patients presenting with minimal residual disease is significantly influenced by the Roach formula. These findings are considered to provide a rationale for the decision on the volume of post-operative radiotherapy.

Keywords: Prostate cancer, Prostatectomy, Roach formula, Adjuvant radiotherapy, Biochemical recurrence