Variation in Radiotherapy Referral and Treatment for High-risk Pathological Features after Radical Prostatectomy: Results from a Population-based Study.

AIMS: Guidelines recommend the discussion of adjuvant radiotherapy post-prostatectomy for prostate cancer patients with high-risk pathology to consider all of their treatment options. We determine whether patterns of radiotherapy referral and treatment post-prostatectomy reflect guideline-based use in a contemporary prostatectomy cohort.

MATERIALS AND METHODS: Electronic treatment records were linked to Ontario's cancer registry. Multivariable regression was used to evaluate clinical and health systems factors associated with referral and the use of adjuvant radiotherapy within 6 months post-prostatectomy.

RESULTS: Among 2663 patients treated with prostatectomy between 1 January 2012 and 30 November 2012, 1261 (47%) were found to have adverse pathology and 492 were referred to radiation oncology ≤6 months post-prostatectomy, of whom 51% received adjuvant radiotherapy. Multivariable analysis showed that patients were more likely to be referred to radiation oncology from a low-volume surgical facility (≤50 versus >50 radical prostatectomy cases, odds ratio 2.50 [1.80-3.48]), if they lived farther from a radiotherapy centre (>50 km versus <10 km, odds ratio 1.73 [1.22-2.46]), if they were seen by radiation oncology preoperatively (odds ratio 1.95 [1.51-2.52]), or if they had adverse pathology: high T-category (pT3b/T4 versus pT2, odds ratio 17.87 [12.14-26.30]; pT3a versus pT2, odds ratio 5.24 [3.95-6.97]), positive margins (non-apex positive versus negative, odds ratio 4.20 [3.19-5.53]; apex only positive versus negative, odds ratio 2.60 [1.71-3.94]) and high Gleason score (8-10 versus ≤6, odds ratio 11.32 [5.37-23.84]; 7 versus ≤6, odds ratio 4.18 [2.16-8.10]). Wide geographic variation in radiotherapy referral rates persisted (range 6-66%; P < 0.0001). After radiotherapy referral, only high T-category (pT3b/T4 versus pT2, odds ratio 5.37 [3.01-9.60]; pT3a versus pT2, odds ratio 2.72 [1.59-4.65]) and non-apex positive margins (odds ratio 2.81 [1.86-4.23]) remained significantly predictive of treatment.

CONCLUSIONS: Variations in referral for a discussion of radiotherapy post-prostatectomy are not mainly explained by patient characteristics. After seeing radiation oncology, treatment decisions correlated most strongly with pathological findings. Understanding the reasons for the tremendous non-clinical variations in care is needed to ensure access to potentially curative radiotherapy post-prostatectomy for high-risk prostate cancer patients.