Individualized estimation of the benefit of radical prostatectomy from the Scandinavian Prostate Cancer Group randomized trial

Abstract

Background: Although there is randomized evidence that radical prostatectomy improves survival, there are few data on how benefit varies by baseline risk.

Objective: We aimed to create a statistical model to calculate the decrease in risk of death associated with surgery for an individual patient, using stage, grade, prostate-specific antigen, and age as predictors.

Design, setting, and participants: A total of 695 men with T1 or T2 prostate cancer participated in the Scandinavian Prostate Cancer Group 4 trial (SPCG-4).

Intervention: Patients in SPCG-4 were randomized to radical prostatectomy or conservative management.

Outcome measurements and statistical analysis: Competing risk models were created separately for the radical prostatectomy and the watchful waiting group, with the difference between model predictions constituting the estimated benefit for an individual patient.

Results and limitations: Individualized predictions of surgery benefit varied widely depending on age and tumor characteristics. At 65 yr of age, the absolute 10-yr risk reduction in prostate cancer mortality attributable to radical prostatectomy ranged from 4.5% to 17.2% for low- versus high-risk patients. Little expected benefit was associated with surgery much beyond age 70. Only about a quarter of men had an individualized benefit within even 50% of the mean. A limitation is that estimates from SPCG-4 have to be applied cautiously to contemporary patients.

Conclusions: Our model suggests that it is hard to justify surgery in patients with Gleason 6, T1 disease or in those patients much above 70 yr of age. Conversely, surgery seems unequivocally of benefit for patients who have Gleason 8, or Gleason 7, stage T2. For patients with Gleason 6 T2 and Gleason 7 T1, treatment is more of a judgment call, depending on patient preference and other clinical findings, such as the number of positive biopsy cores and comorbidities.

Fig. 1

The 10-yr predicted risk reduction for death from prostate cancer among men treated by radical prostatectomy versus watchful waiting in the presence of a competing risk (death from other causes) for men with Gleason 6 (black line), Gleason 7 (dashed line), or Gleason 8 (gray line) disease. Figures are stratified by stage and adjusted to a prostate-specific antigen level of 10 ng/ml.

Fig. 2

The 10-yr predicted risk reduction for metastasis among men treated by radical prostatectomy versus watchful waiting in the presence of a competing risk (death from other causes) for men with Gleason 6 (black line), Gleason 7 (dashed line), or Gleason 8 (gray line) disease. Figures are stratified by stage and adjusted to a prostate-specific antigen level of 10 ng/ml.