Impact of positive surgical margins on secondary treatment, palliative radiotherapy and prostate cancer-specific mortality. A population-based study of 13 198 patients

Abstract

Background: The results of studies evaluating the impact of positive surgical margins on prostate cancer-specific mortality have been inconsistent. We, therefore, evaluated the impact of surgical margin status on subsequent secondary treatment, palliative radiotherapy, and prostate cancer-specific mortality.

Methods: A total of 14 837 men treated with radical prostatectomy (RP) during the period 2001 to 2015 were identified from the Cancer Registry of Norway. Of those, 13 198 (89%) patients had complete data on the preoperative prostate-specific antigen level, pathological T-category, Gleason score in the prostatectomy specimen, and margin status. Multivariable Cox proportional hazards models were used to evaluate the risk, and flexible parametric models for the cumulative incidence were fitted to predict the probabilities of secondary treatment (salvage radiotherapy or prophylactic breast radiation), palliative radiotherapy, and prostate cancer-specific mortality.

Results: After a median follow-up time of 5.2 years (3591 patients with ≥8 years of follow-up), positive surgical margins (PSMs) were independently predictive of secondary treatment (hazard ratio [HR] = 2.43, 95% confidence interval [CI] = 2.21-2.66) and palliative radiotherapy (HR = 1.45, 95% CI = 1.03-2.05). After 10 years, the absolute increased risk for palliative radiotherapy in patients with PSMs after RP varied between 0.1% in pT2 tumors with a Gleason score of 6, to 12% for pT3b tumors with a Gleason score of 9 to 10. PSMs were not independently associated with prostate cancer-specific mortality (HR = 1.14, 95% CI = 0.82-1.59).

Conclusion: PSMs were associated with increased application of secondary treatment and palliative radiotherapy but were not predictive of prostate cancer-specific mortality. As the use of palliative radiotherapy was only marginally increased in patients with PSMs and the lowest-risk disease characteristics, avoiding PSMs may be of greatest prognostic relevance in patients with higher-risk disease characteristics.

Keywords: mortality; prostate cancer; prostatectomy; radiotherapy; surgical margin.